We started out with local school boards because no other level of government thought it was appropriate or possible to raise and expend the money to run schools, and to run them properly. American education was conceived of as a locally-inspired, locally-financed, locally-supervised activity, standing independently of all other forms of government.
A lot of dreamy-eyed idealists think that this is the way all public governmental exercises should be... local methods, locally controled to suit local purposes, because all that is big is bad, because big drives out freedom. Maybe that's true, but one thing you get out of local control is mediocre education. Good quality becomes controversial.
In France, which is an example I keep coming back to because I know a lot about it from my wife and it is so different, they exercise central control to a degree that Americans would think is crazy. You can be assured that in all France from the north to the south, every kid is turning the same pages in the same books on the same day. Local school boards don't exist at all, and not just books but daily curriculum is decided at the top. Probably for more advanced high school courses there is greater flexibility, but only because it's very hard to standardize absolutely everything. The French test to a common national standard, too, and the tests are extremely important. When you're twelve you take a test that determines what high school track you'll go into: vocational or academic. Most go vocational; they graduate at age 16 and hit the work force. There's basically no going back; at 12 you find out if you will be a practically-minded worker or a book-learned decision maker for the rest of your life. The academic track splits between the humanities and the sciences; the student gets to choose his track, but his advisors are strongly influenced by his test scores. At the end of high school, which goes until age 18 or 19, you take a test called the baccalaureate (le bac), which if passed, is probably the equivalent of five semesters of American college. You have a couple of years to re-take it, if you fail. Most fail, and go into the work force in some paper-shuffling capacity, or selling cars, if they're lucky. Those who pass go on to college. French university is basically 100% state funded, but the college you get into is determined by nationally standardised tests (of course.) Interestingly, one college (ENA, or Ecole National d'Administration) is where you go if you will become a judge, a top bureaucrat, or a manager of a state enterprise. It sounds weird to Americans, but to the French mind, if you create a training program for your best, it is logical that you would staff your top positions all from graduates of that program.
My wife says that the French education develops the best in the best people, but the shortcoming is that if you screw up once, you are shunted onto a secondary career track that you will never leave. In America, she says, you get second chances.
I've looked at her school books; the geography book she had in sixth grade (before they break you into separate tracks) would be considered too challenging for most American high school students. (Come to think of it, they don't mess with geography in America any more.) It's really impressive. In fact, I doubt that a lot of American teachers would be competent to handle standard French curriculum.
In America, they don't try to develop the exceptional kids; they just aren't given any room. Yet in France, they manage to make challenging material available in the ordinary curriculum. It's an accomplishment. They also have a successful vocational program for the majority of the kids who just aren't going to gain anything from a college prep high school. In America, everybody gets the same education and the same opportunity, but the college prep is dumbed down so that everybody can get through it.
I can't say that I like the rigid tracking of the French, or their goofy faith in credentials. But, they do things we don't believe are possible.