One place to start could be looking at some of the specific ways you feel your kid is being "defiant" and look for a positive way to reframe what you're seeing. Maybe he's someone who, for instance, always thinks for himself... even when you rather he just do what he's told ;) Maybe he's someone who has definite opinions and learns by bouncing those opinions off the world and seeing what happens. Maybe he's really very sensitive and tries to stand against anything he sees as injustice. I don't know your kid, so I'm just tossing out examples.
My kids are very strong minded and tend to learn experientially - which for them can mean forming theories and testing them. Seen from one perspective, that makes them "defiant" - they're not the sort of people who do what they're told, unless it's convenient for them. That's not a result of unschooling, although the fact that my stepson is that way led us to unschooling. Life got so much easier and sweeter the more we became open to the idea of helping him explore the world in ways that worked for him rather than "helpfully" telling him the "best" way - he didn't want our answers, he wanted his process.
And my daughter is similar - as a toddler she never asked what or how or why, she said "because..." and explained the world to us. She wasn't always right, but you couldn't convince her of that. It was so much better to let her have her certainty - amazingly, she didn't mind having the world prove her wrong. She just didn't want to be told. Like she didn't want the spoilers.
She also has some sensory issues - which I've discovered a lot of parents read as defiance, so it's worth mentioning in case it's an issue for your kid. A lot of the time when kids are "refusing to act right" or "making a scene" or "trying to get attention" they're really reacting to overwhelming sensory stimuli - whether that's a misplace seam in a garment, or the texture of a food, or the acoustics of a room, or any of a thousand other things. And no-one responds well when they're overwhelmed :P Happily, it's possible to help kids to deal with the world without being overwhelmed by it, but it's a process that actually starts by helping them find ways to minimize or even avoid the too-intense stimuli in the first place, so they can learn to deal with the world at their own, unique pace.
In more general terms, the question of "how do you teach?" comes down to thinking about what's important and interesting to the person doing the learning. When kids' interests happen to line up with parents', then any kind of parenting looks good. When they don't, whether it's considered good or bad parenting comes down to how much what you do looks like what everyone else does. If you look just like you're neighbors, then you have a rotten kid. If you don't, you're a rotten mom. That's the way public opinion works.
The reason you get such a mix of parenting stories, with some looking like success and some "failure" is because what's important and interesting to individual people (children) will be different at different times and in different ways. When teaching (including modeling) lines up with learning, it looks like teaching works. When it doesn't... well, that's practically the definition of "bad kid".
Courtesy, or the outward show of "respect" is a complicated song and dance. That's important. Some people do it easily - we all have natural aptitudes! Some don't. It helps to think about all the various components of courtesy: word choice, body language, eye contact, tone of voice, inflection, pacing of words, sense of timing. To a lot of people (children) it Feels like an act - to some it feels fundamentally dishonest, which is why you get words like "authenticity" and movements like "radical honesty". Courtesy and respect can feel like a great big lie that other people require of you. And for a child, who's probably also being told that lying is wrong, that's a gigantic mixed message. Tell the truth, but never about what you really want and think and feel, especially when it's something adults don't want to hear.
Think about "back talk" in terms of honesty for a bit - your kid is being authentic with you, telling you what she really thinks and feels. She disagrees with you and isn't candy coating that with sweet words and tone. Maybe she isn't doing that because the song and dance seems like a big fake in the moment. Maybe it's just a whole lot of work, work that she can't quite manage when she's distracted or stressed in some way (hungry, tired, frustrated, excited, etc). In a very real way, she's being incredibly respectful of you as a human being, because she's letting you know what's important and interesting to her in the moment. She's just doing the performance wrong.
As a parent, that means that it's up to you to decide when that performance is more valuable than your kids' honesty. That's a big ethical dilemma! Over time, kids do learn social skills from people they care about because human beings are social in nature. We like to be nice, we like to have friends, we like to smooth our own ways. When kids aren't bombarded with nos and don'ts about things that don't make sense to them, they tend to develop a better understanding of the rationale behind courtesy rather than just a bunch of rules about the performance. But depending on the social environment you live in, it may not be feasible or safe for your child to be honest. It may be necessary to require them to perform some of the time.
So, you look for ways to make it easier on them. You apologize for not being able to accept their honesty in every given moment and offer alternatives: "yes, I want to hear your story, but later, sweetie." You look for ways to keep your kid out of situations they can't handle - where they won't able to perform because it's too hard for them. You look for lower key situations where your kid can practice some parts of that performance. You Create those situations by being patient with your child's honesty and continue modeling courtesy. You offer up hints and coaching when it seems appropriate. You perform for your child and gently deflect criticism so their learning process isn't derailed.
It's frustrating, as a parent, to have the socially gauche kid, the one who can't just fake compliance and cheer like Little Miss Sunshine next door. I've never had "good" children in that sense... but I also didn't start out unschooling so I know that I wouldn't have gotten "good" children the old fashioned way, either. They don't all come that way. What I have seen, though, is how, over time, kids have reasons to want to connect with people and will learn the skills that make that easier when they can. I've seen my wild, impossible child grow into someone who moves easily between a variety of cultural groups because he's had the chance to learn to understand courtesy and respect on a gut level that shows even when he doesn't have the exact right words or mannerisms. I've seen my super-introverted don't-look-at-me child give thoughtful information to emergency professionals in such a way that they saw her as solemn and sympathetic, rather than sullen and disrespectful.
None of that would have come from "teaching respect" because my kids don't appreciate being taught, and have let me know that pretty clearly. It has come from time and maturity, and chances to learn in ways that are meaningful to them.
Something else that's worth keeping in mind on the topic of respect/courtesy is that homeschooled kids often learn more adult social skills from an early age. That can make them seem weird - it's part of the stereotype of the oddball homeschooler. It can also make them seem disrespectful because they're approaching adults with the same level of respect and courtesy that adults give to each other.
There's a big power dynamic between adults and children - children are, in a sense, a "lower class" and it comes out really, really starkly on the subject of courtesy and respect. It gets rationalized in terms of "they have to perform in order to learn" but that doesn't account for the degree to which adults feel resentment when kids don't do the things we expect from our lessers. We expect our lessers to comply, to smile at us, to conceal their true feelings in preference for ours, to stroke our egos. That's a big part of what it means to show "respect". It's not about actually respecting another human being in the sense of giving a hoot, it's about demonstrating that you know your place.
And depending on the circumstances of your life, showing that you "know your place" might be pretty important... although there are different trains of thought on that subject even among adults. It can help to remember that there really isn't single rule for when it's better to keep your head down and when to stand up and say, "no way, fuck this noise, I am as human as you are." Insisting that our kids always "show respect" doesn't offer them the true complexity of adult life where sometimes doing the "right thing" is the wrongest choice of all.
"At some point they'll have to enter the mainstream.... That's where they will struggle."
This actually isn't true, about kids struggling. Unschooling kids adapt as well as their natural aptitudes allow - as well as or better than school kids with similar aptitudes. It seems counter-intuitive, but it's a good example of how teaching doesn't guarantee learning. Being "in the system" doesn't necessarily make it easier to handle the system. Sometimes it makes it harder, because kids burn out academically, or get overwhelmed socially, or get so stressed they struggle to function.
Unschooling kids are used to making choices about things that matter to them. It doesn't mean all their choices are good ones, but by the time they're young adults they've had a chance to learn that, to learn that sometimes you fail and move on. Sometimes you get stuck and need help. Sometimes things don't work out the way you want and you regroup. And because they haven't been pressured to succeed, they're better equipped to deal with those possibilities. That's an asset in higher education.
They're also used to persevering when things matter to them. That's something else that can seem really counter-intuitive to people who aren't used to natural learning (which includes almost all unschooling parents, at first!). Schooling presumes that kids need to be taught to persevere - but kids are actually really good at it when something is important to them. Ironically, the kinds of things that motivate kids to persevere are also the things parents tend to wish kids wouldn't do. Kids will struggle with a project until they're crying and swearing and throwing materials and Not Want to Give Up. And parents respond with "stop that nonsense and go play." And then wring our hands at how poorly motivate our students are.
Given the chance, kids are actually great at learning the skills they'll need in life. Even the weirdly artificial kinds of contemporary life we've built for ourselves. Sure, they need help and support, but they don't need lessons on how to be better humans. They're darned good humans from the start .
One of the stereotypes about unschooling is that it's just for kids who are spectacular in some way. Well, I'm going to break a mommy rule and say: my kids aren't particularly special. I mean, I adore them and all, but they're not geniuses. They're quirky and strong willed, and in some ways that makes unschooling easier - it keeps me honest ;) - but nothing earth shattering here. What unschooling lets them do is be who they are and focus on what's meaningful to them. It lets me, as a parent, focus on who they are and what's meaningful to them, rather than what they "should" be doing to stay on some educational timeline.
Unschooling kids don't learn because they're geniuses, they learn because people are naturally curious. The trouble is that there are things adults would really rather kids learn for reasons that, frankly, aren't about kids as they are. They're reasons about an imaginary future that may not be related to our kids' strengths and interests and personalities. And they're reasons about our own desire to seem to be "good parents". So it's easy to read articles about miraculous unschooling poster children and think "well that's not my kid." It's sure not either of mine! Most unschooling kids are just kids. Wonderfully unique and beloved, but just regular kids doing regular kid stuff. The kind that mostly doesn't make for good blog posts. And yet they still manage to pick up basic skills and a fairly standard body of culturally relevant knowledge - because people are curious and want to know how to navigate the world they live in.
In some ways, one of the most striking things about being an unschooling parent is getting to see the extent to which school obfuscates learning. All that hard work school kids do turns out to be a lot of sound and fury.
There are several different issues with the idea that your teens are "lazy". The first is that it takes a good bit of time for kids to re-learn how to self motivate! School - and often homeschool, too - strips that away from kids. "Deschooling" as it's called takes months - for teens, expect nine months to a year, and know that, depending on how big of an impact school had on them, it could even be longer. :( It helps to imagine that your kid has had a serious long term illness and needs time to recover. Let them chill and recuperate. Hang out with them. Watch some shows and play some games together. Gently offer to do fun things together, but don't push. Take time to get to know each other in a different way than before.
Another big thing to know about young teens, though, is that the big developmental processes going on in their brains takes a lot of energy! They may need a lot of down time, time to ponder, time to daydream, they may even sleep more. Around the online home/unschooling community at large, this has been dubbed a "cocoon stage". Not all teens "cocoon" but many do.
But the other thing to keep in mind is that natural learning won't look like school learning. It will look like kids pursuing their own interests - even their non-academic interests. Things like doing hair and playing video games. So it will help you and your kid for you to treat those as "legitimate" interests from which they will, inevitably learn. There's plenty to learn! And it doesn't need to be directed toward any particular goal. School sets you up to think there's this big race toward a finish line, but it's not true. It's really okay to give your kids a chance to breathe and discover who they are and how they learn, naturally.
Something that comes up a lot in the autonomous education /unschooling movement is the way kids learn these kinds of skills without necessarily being taught. And often the ways they learn them are by doing exactly the sorts of things that parents and teachers commonly try to limit. There's a disconnect in adult expectations between the skills that we want kids to learn and the way we want them to learn those skills.
So parents will panic when a kid shows good attention span or focus when those aren't directed at chores or school work (Kohn mentions worthy subjects). Or worry when a kid keeps trying and failing at a game over and over, maybe crying and swearing, but persisting. Or when a child insists on using Just these materials in Just this way to do a project. Or creates a detailed plan and wants to stick to it, despite obstacles. When kids do those things independently - self confidently pursuing their natural curiosity - it's often seen as problematic.
What does it mean or look like, to trust a toddler or young child to make decisions?
Another way to frame this whole question is to step back from ideas about choices a little and think about how communication works. I'm thinking in particular about a "we need to leave" scenario. There are plenty of reasons to need to leave very soon - wanting to avoid getting stuck in rush hour traffic, needing to pick up something before a store closes, having another kid starting to freak out (btdt)!
In conventional parenting, communication is mostly one way: parents tell, kids listen. So even if you're trying to get away from that, it's easy to fall back into that pattern. "Giving simple choices" is a kinder-and-gentler tactic for telling, but it's not necessarily the best way to communicate with someone you care about.
Communication starts with listening and observation - isn't that why we want our kids to listen? We know that. But that knowledge gets tangled up in our own baggage that's saying that we're the adults, it's our turn to do the telling. We forget to listen and observe. Or maybe we didn't learn it very well from our own "do as I say, not as I do" childhood experiences ;)
It's also important to recognize that tears and protests are valid forms of communication, expressing valid feelings. It's okay for kids to be unhappy when things don't work out the way they want. The goal isn't to get compliance with a smile, it's for kids to feel like parents are on their side in the larger context of their lives. Sometimes that means carrying a crying child to the car with sympathy, "hearing" their pain, even when there's no good solution to it in the moment.
So in the case of needing to leave, it helps to start by thinking about what you know about your kid. Maybe you're getting the idea that transitions are tough right now - that's normal with toddlers - in which case offering a choice could only prolong the agony. Maybe you know that your kid likes a lot of warning, warning that doesn't need to be framed as a choice, just: "five more minutes, dude!" Maybe you know that your kid is really good at communicating verbally and will be able to negotiate. Maybe it's just a matter of saying "wanna get ice cream?" Or asking "how can I help?" All of those things depend on individual personality and development and can take some trial and error to figure out. And sometimes there's nothing to figure out beyond how to carry a crying, writhing toddler to the car with as much sympathy as you can muster, because transitions are hard right now.