I don't know how fixable that one is via just spending: There's a significant component of just selecting for student quality, interest in studying and parentally funded support when a student is struggling. It's a non-trivial part of the US' love of sprawl: Fewer kids of different levels of means will live near you. So when parents say they buy a house for "good schools" they aren't just saying funding per student. And yes, we have this too even in areas without a significant racial component. Making sure only very expensive houses are around you, and keeping housing prices up, has an effect on schooling, even if just by selecting for kids of parents that can afford the big houses.

Ultimately the American parent is paying for the kids education either way: Either by buying a more expensive house near said "good schools", or by paying a private school, which is allowed to be selective in their admissions and match students. Making all schools actually be about the same is not just a matter of funding them equally, but you'd have to end the student segregation (even when it's in legal ways(, which is quite the challenge.

For instance, around me, there's some really bad school districts that end up grabbing very large mansions. But what happens there is that none of the kids of people living in those mansions actually go to public school. So while it might not be economically difficult to up the funding of the schools near poorer neighborhoods, I don't even necessarily think that they will get the same outcomes for the same funding: The selection component is going to change performance.