the per-pupil number is a deliberate red herring. spending increases only cover increasingly expensive private contracts, expensive middle-managers who often contribute little of value in terms of actually educating pupils, and liabilities

teacher pay-rate and total comp are better indicators of defunding and they are dismal: https://nces.ed.gov/programs/digest/d21/tables/dt21_211.60.a... - this shows pay rates have stagnated since the late 2000s with some trending downwards since

even then the rising costs don't reflect an increase in percent-of-GDP spending - that's actually gone down in the past decade: https://nces.ed.gov/programs/digest/d22/tables/dt22_106.10.a...