Schools in the US are funded by property tax. It makes no sense to do that unless the goal is to keep everyone in their place and prevent kids born into poorer areas from competing on equal footing with the children of wealthy people.
Schools in poor areas have higher funding than schools in rich areas, the property tax funding is only one part of where schools get their money from. See this report for example: https://nces.ed.gov/pubs95/web/95300.asp (it's a bit old but nothing substantive has changed).
The paper you linked to opens its summary of results with the following:
"How do education expenditures vary with alternative district and
community measures? Students in districts enrolling the lowest percentages of students in poverty and the lowest percentages of students in need of special education services received the highest expenditures."
