The teachers are a little different though. When they go on strike, the most directly affected people are the students, who they aren't negotiating with. Second hand effects are on the parents, who again they aren't negotiating with.

It's only via third hand effects that the other party is actually affected, because the parents have to make the admin's life hard.

So teachers consider that their first duty is to the students. Also they are there to help the students to begin with.