My wife works in a very, very poor school and we don’t even try with the PTA, her and I fund these kids for trips on our own..
Actually, after the trouble my wife was having with them, she said last week that from now on we will just give the money direct to the teacher so they can use it as they see fit.
Today she came home and one of the teachers said something like “Well, we’ll just follow the path of least resistance - even if it means using our own money more”. (And I know that a lot of the teachers already use a lot of their own money for special supplies, etc.)