AP and IB needs the great teachers, great teachers might be attracted to the AP/IB because there might be less feral students running the class from the back seats. Self selection into AP and IB is a real thing LOL. The whole point is that your good curriculum might not be pervasive in the backwaters of the USA. AP and IB in public schools means that there is at least an attempt at offering rigour to all students, vs ones who can pay for private schools or access academic charters. In my location, the IB schools are the academically superior schools. Choosing private HS here is not going to be for academic rigour. The privates limit access to APs because they won’t get the great scores as confirmation of the ROI of school fees. Publics don’t have to justify that.