If so there must be a lot of union teachers posting on this forum
Not necessarily online. But in the schools, the unions push the agenda.
My brother and daughter were/are school teachers and I was in one of the big unions
in my job (NOT a school job). The unions are led by true believers and they drive the direction things go.
And the union zealots are in touch with policy makers. In my estimation the majority of members
are, if not apolitical, then by no means zealots.
But they will go the way the union pushes them without pushing back too much.