It's obviously not all supply and demand because school zones are a zero-sum part of house prices. Only the richest people can afford to pay the good school zone premium. If too many houses get built there, the schools shrink their zones so you can't increase housing supply to get out of that. You also can't increase the supply of good schools because that's mostly determined by the relative income of the parents, which can't be increased, by definition because it's relative.