> I think the idea is that if it’s important to rich parents, they will grudgingly fund education for everyone.

it doesn't cost more for a teacher to open up an algebra book and teach from that instead of from the pre-algebra book. unless there are scheduling difficulties which somehow prevent one classroom's worth of students from being crammed into the same room in the same slot, the imagined lack of money isn't going to impact the contents of the curriculum.

this isn't like when we thought we needed to cram schools full of computers and they were going to cost money. one math class is an expensive as another to teach. we don't even need new textbooks. hell, we probably don't even need textbooks, just have them do exercises online or something.