Students/families at higher performing schools have far lower need for support systems.
- in higher performing schools, parents fund a number expenses directly through a very active PTA, so those expenses don't show up in the school's official spending per pupil, while
- at lower performing schools with less active and more impoverished PTAs, those same expenses must be funded by school budgets, driving up their official per-pupil spending.
At the low performing school, the extra public funds received are often paying for support staff for serious social issues. There is little budget for the "nice to haves", and even when there is, the school staff has it's hands full managing the basics, so it's not always effectively utilized.
Sure, that's a factor too, but I'd still call it a social service issue since it ultimately results from the historical disinvestment in the communities that today have low performing schools.
There are reasons that the roofs didn't get repaired and the lead pipes didn't get replaced in those schools: because middle income people took their lives, businesses, and tax dollars out of those communities starting in the late 1960s, both by migrating to newly built suburbs, and also by ensuring their tax dollars never went toward the communities they left.
Look up the opposition to "Robin Hood" school funding from the 80s and 90s. Where I grew up it was largely about keeping suburban tax dollars out of inner-city school districts.
Blame education schools and their failing "every student can simply learn their math on their own!" approach. Total self-serving garbage, devised to cater to the ego of naïve prospective teachers and their expectation of not doing any real teaching work.
"there are substantial disparities in abortion rates in the United States, with low-income women and women of color having higher rates than affluent and White women"