You're right; I did make assumptions, and looking back, I'm the first to admit that. What I meant by "everything a child needs to know" I meant in order to sit and pass their exams. I realise that the lessons you learn at school are only a tiny fraction of what you need to know for life, and I realise that those other lessons are learned at home, and through exposure to society and other situations.
I also agree that several parts of the curriculum is outdated, or unnecessary. I for one will probably never need to know about trigonometry, or loci, which my maths teacher insisted on teaching me, but someone in the world WILL need to know it, and therefore it's worth teaching, in my opinion. I agree that a parent knows their child better than any school, but I do t believe a parent should take the child away from a well-rounded education p, to home school them and teach them things that only THEY deem important. We can all raise our kids to be as we wish them to be. I'd be over the moon if my kids turned out to be doctors, so lets throw them into double biology, but what if they want to be carpenters? They will then be over-educated in one field, and under-educated in the one that matters TO THEM. How can I teach them to build a chair if I don't know the skill myself? I just think its very irresponsible to assume you know enough to teach your child adequately, when a school is set up with that specific function in mind, and they have sought experts in those subjects to teach those skills properly.
And of course self-motivation is important, and I encourage that, but it's a teachers job to engage their students and to make them interested in that subject. I am an atheist to the core, yet my religion teacher in school was one of the best teachers I've ever had, and she made the course so interesting with her teaching methods, that even someone as cynical as me enjoyed being a part of it. Of you're a good enough teacher you can make even the most disinterested student flourish. Also I don't believe for one second that a seven year old, for example, will choose to learn about something they're not interested in, when given the choice between that and something they find to be better; when given the choice, it's human nature to go for the thing that interests us more, but other subjects need to be taught too. Your son may pick out maths stuff from the shelf, and that's fantastic that he does, but he may dislike something different; simply because it doesn't interest him. If you were to put them side by side and offer him the choice, he's much more likely to pick the thing he likes than spend time on something he doesn't
I have to admit that I wasn't aware people had a support network like that; every case I've seen, a support network has not been mentioned, and it has never been implied that such a thing exists. I'm glad there is such a thing, because like you say it allows you to pool your information and skills to provide a more well-rounded foundation for the children.
Having said all of this, I wouldn't feel comfortable removing my child from an education that I know to be successful. I believe the teachers are picked because of their qualifications, their thorough knowledge and because they know how to teach children, and that's more than I know. I'm not a stupid person by any means, but I'm well aware my children wouldn't receive as good an education from home-schooling; in terms of what I could offer them. Perhaps I could, but I'm not willing to risk it and risk jeopardising my kids' futures. Good on those that are willing to risk it, I'm just not one of those