I hope you won't mind, but I'm going to make a guess that you probably don't have children. My guess is that, if you did, you would decide to homeschool, too. :-)
Your school experience and mine are nothing like school today. Picture yourself with a daughter, for example. You probably would teach her to read at a young age, like I taught my son. Then you would take her to preschool registration, mention to the teachers and administrators there that your child can read, and watch them shrug off that information and stick her in a class to learn colors, shapes, and how to write the alphabet, even though she can already do all those things and more. The only thing your child will be learning new is how to line up and behave in a classroom environment.
If your child's birthday falls in the middle of the school year, you might even be able to pull some strings and have her moved up a grade level. But then you'll notice there are children two years older than her in her class, and some of them are cursing, and now the school wants to show her a video called "Family Life" so that she will learn to accept "all types of families." Meanwhile, the middle school she soon will be attending has a "lockdown" now and then so the police can search for drugs. Academically, she is still learning more at home on her own time.
I would almost bet that, given those circumstances, you, too, would pull your child out in an instant. ;-)
I was definitely speaking from experience as a pupil, not a parent. And I think some home-schooling always goes on; kids don't learn everything in school. I doubt I would have done that full time, though, since I am dedicated to having a full time career (which may be a very good reason I don't have kids in the first place!).
There were certainly kids older than I when I was in my various grades, but I don't imagine that school overall is very similar now to my student days (however, the rule probably hasn't changed about saying "there are children two years older than SHE", not "there are children two years older than *her* in her class", as in your post). My mother was a schoolteacher as well, so she was never off duty when it came to correcting my grammar! :)
I have never heard of middle schools right near us having "drug search lockdowns", so that may be more a situation of the particular district or kind of neighborhood, than nationwide school policy.
If your message is that things have changed in the last thirty five years or so, I don't doubt it. They've changed in every other aspect of life as well.