One of the highest truth/word comments I've read in a long time. The real issue with education in America is that everyone a) thinks it is someone else's problem and b) thinks if they just change x we will rocket to the top.
We also still spend a lot of money on the students who least need it. Due to the influence of property values on education spending often the most affluent areas spend the most per student. We also spend a lot on 'special needs' students who have a limited capability to be educated. But, what matters most is how well the average student is educated and we don't spend a lot of money on that.
Inflation adjusted dollars and PPP attempts to balance housing, food, and healthcare costs. But schools need to compete with the rest of the economy so it's balanced not on how expensive food is, but how much janitor's / teachers / middle managers could make working somewhere else. R&D has reduced the amount of man hours required to produce a hammer, it has not reduced the amount of man hours required to teach subtraction.