Its probably because obviously not all districts are like this, and its likely that the author's entire school isnt even like this. The blog points out small parts of a single school district in the entire country.

Giving struggling schools less money when they require larger and more diverse funding almost definitely isnt the answer. The average public school teacher still spends a huge amount of money every year to buy stuff for their class to use, and we expect them to continually do that throughout their career.