In my state, these kinds of expenditures are funded through district bonds which are a one-shot property tax increase for a set period of time, whereas teacher salaries and other yearly expenditures are funded through levies which have to be periodically increased to keep pace. Additionally, whenever we pass referenda to bump the base pay for educators, the state legislature is very very quick to turn them into unfunded mandates. It's not an issue with the districts or the voters, it's fundamentally a problem with the legislature and how they earmark funding.