> Even if they're bad on average, some of them will probably figure out how to make an actually good US school by sheer luck. Once we have that, the others have a model to copy.

How could anyone know that, if each school has its own curriculum and exams? If you got 4 gold stars out of 5 on your reading comprehension and I got three palm leaves out of 4 at literature interpretation, which one of us is getting a better education?