Yes. It exacerbates the inequality because most of the top-50 richest PTA schools can afford extras that boost student engagement or provide in-class assistance via teaching assistants thus lowering the student:teacher ratio.

When a PTA can afford to pay for extras that the school doesn't or can't (e.g. extra art & music teachers, computer labs, playground monitors, etc.), a student's quality of life at such public schools is generally objectively better compared to students at public schools without the extra budget. The year-over-year budget boosts are profound.

Yes this is true. But it doesn't seem that big to me: 10% extra budget isn't nothing, but it's at a few schools which are competing with private schools, which (I think) charge more like 2-3 times as much.

And this is the top fraction of 1% of public schools. The merely top-20% schools, nice suburbs far away from wall street, they raise a fraction of this. I don't think it can explain very much of what's different there compared to the bottom-20% schools across town.