Yup all of us are horrible greedy leeches.
No, I never claimed that individual members of the teachers unions are the problem.
Yet you have problems with the unions; which is the collective sum of it's members. It's perfectly reasonable to dislike leaders and governance of a union (I know I do with mine) but to say you hate the union because of it's leadership is a bit of a slight against the people who make up that union.
The topic is called "Opinion of teachers' unions", but that doesn't mean everyone will answer it in reference to the sum total of their members. To do so would be to make this a rather drab topic, considering the diversity of people in teachers' unions, like any other group.
To put it more plainly, I am rather neutral on teachers in general. I am rather neutral on most groups, aside from ones that voluntarily self-identify with repugnant ideas, causes, & actions. I would qualify Klansmen or child molestors as being HPs in general.
My point is, to answer the question as referring to the sum total of the members of teachers' unions ultimately makes the question less to do with teachers' unions & more to do with the answerer's value judgments in re groups. I highly doubt that the poster of the topic intended replies to be biased in such a fashion.