School is probably the most efficient and effective way to introduce higher education in a nation that is just moving towards post-industrial post-agrarian status. I think it has a terribly important positive role in such places. Unschooling may be the oldest, most natural way for humans to learn, but it works well to pass along the skills and knowledge already widely present in family and community. When you're looking for a way to move an entire population forward to a higher or different sort of educational expectation, I think mass education by trained teachers is the way to go. I've often thought that unschooling must seem incredibly bizarre and probably arrogant to citizens of developing nations. So yes, I definitely understand why your perspective is a little different.
1. The thing about unschooling is that children learn and grow in an environment that does not separate learning from living. We read a lot about unschooling young children on boards like this, but less about what unschooling tends to look like amongst teens. As the mom to three teens who have unschooled fully or partly through their "high school years" I can tell you that they tend to get out in the real world a fair bit. They tend to have mentors and contacts within the community, within their fields of interest. They have a lot more flexibility than school students in terms of gaining experience in those areas. They have more experience in direct contact with the working world. My eldest dd, who wanted a career as a musician was able to: travel in order to get higher level training, travel for gigs with orchestras which earned her experience, money and lines on her resumé, work as an accompanist for an adult choral ensemble, work as an accompanist for young string students, and get a part-time job in the service sector at a café to learn one of those "day job" skills that every freelance musician needs. She was able to build a robust network of contacts, people who would write her letters of reference, who would put her in touch with people she "needed to know" and so on. My ds, who is interested in computers and digital media, has spent hundreds of hours building websites, mixing music, trouble-shooting system failures, swapping out graphics cards, volunteering with a computer recycling program, fixing other people's computers, editing movies, learning Photoshop, etc. etc.. He has professional references in the computer repair sector. His plan B is to be a musician, and he's already earning money playing gigs with his viola. I'm pretty sure all my kids will opt to go to college; eldest is there now, the others plan to go. I anticipate them having the qualifications and resumés they'll need to do whatever they want, and probably a better sense than many schooled children of what it is they want, by virtue of having been out and about in the real world a lot more.
2. While I believe strongly in the primacy of family, I also believe strongly in the value of community. I don't want my kids to be at the mercy of an institutional version of discipline and values for a huge portion of their waking hours, but I am very happy if they spend lots of time away from home and in contact with other people. I just want to retain my (and their!) ability to observe, limit, filter or temper influences that feel wrong and undermine their happiness and our values. I love the teachers at our local school; I think most of them have wonderful hearts and nothing but their students' best interests at heart. But there's still the reality of a few people there who believe in a top-down authority-based model of judgement and discipline, and of the peer-driven values and social garbage that tends to take root when large groups of age-matched children are together for large chunks of time with no caring adults nearby to be witness to their interactions. My kids probably spend far more time involved in real community life. They know every member of two community choirs, all the stall-keepers at the community market, the dozen elderly ladies who do step-aerobics at the community gym, they know every grocery store cashier and café staffperson by name, they volunteer at the community garden, at concert performances, and so on. When it comes to our village, my unschooled kids are out living in it, while their schooled peers are sitting in classrooms at school.
3. I really think the best resources for giving a person an idea of what unschooling entails are places like this. You can't write unschooling up in a book easily, because it looks completely different for every child, for every family, in every community. My 9-year-old is musically and mathematically precocious, lives near a rural village in the mountains, has doctors and a musician for parents, loves formal academics and is very outgoing. For a 9-year-old who loves imaginary play and painting, lives in a city, hates pencil-and-paper work, and whose parents run a food wholesale co-op, unschooling is going to look totally different. The only thing they may have in common is this: that the reason they learn anything is because it has meaning for them which motivates them to learn. So I've found that tapping into the vast breadth of individual experiences with unschooling is the only way to begin to understand. What does unschooling look like? It looks like the whole world!
I would say that unschooling is practical anywhere it's legal -- if the child's parents have basic high-school-level education and access to a variety of real and/or virtual resources.