PiqueABoo: I don't apply it to all teachers at all, but the unions (and some teachers). They fought for more pay, and got it. They fought for less teaching time, and got it. They fought for the dropping of "admin tasks" and they got that too. So now schools are faced with teachers who cost more, teach less, and do very few "admin" duties. Students still have to be taught and admin duties still need to be carried out - so naturally this then falls to everyone else (who don't have the luxury of über-strong unions, or decent/fair pay & conditions, or the amount of holiday time...)
The education system is so unbalanced that this behaviour from schools is extremely likely and, it seems, popular.