I don't think the US school system is that good, honestly, but I'm not a US resident or citizen so don't take my word for it.
I just want to comment that home schooled ids can still socialise with their peers. They can have lots of extra-curricular activities, such as a sport, or learning to play an instrument, or a game, etc. They can go to some regular activities in the community, as well. And they might play with the neighbours.
I'm sure some children who aren't home schooled are more isolated than some who are. School isn't the only way to meet other people and might not be the best context either.
I didn't grow up in a country where homeschooling was common either, and I do find it interesting. Mostly it raises questions for me: how do the ids get their credits, do they take final exams? Are there regulations on what you have to teach them or even what you're not supposed to?
I think teaching is best done in small groups, so from a purely theoretical point of view I would say the best would be for a block or neighbourhood to teach their kids together, each teaching what they're good at.
I think it would probably be difficult, once they reach high-school level, to teach them everything if you're just one person. On the other hand, that level of one-to-one teaching (or other small groups) allow for more individual classes, that match the actual level of each child and doesn't force them to follow the same rhythm as a whole class, which might be too fast or too slow for them depending on the subject.
I think if I was raising a kid, I'd want to home school them until they're 6 or so at least, give them a solid foundation.