Unfortunately I have heard the same. I know 3 male high school teachers and the stories I hear are unfathomable, you could never convince me to teach at a high school.
Many low-paying social service jobs are filled by spouses of people with high-paying jobs. This can lead to an elitist culture, even in the lower levels.
There is also a lot of overlap between social service orgs and religious orgs which can lead to a conflict between mission and church doctrine.
All in all, I perceive it as being as diverse a field as the rest of society, and filled with many viewpoints. It doesn't seem dominated by one "side" or the other
For the record, I don’t support American liberals or conservatives, who both waste too much time avoiding confrontation with the root problem: capitalism.
I think your goal is to attack the person and and not the idea, which has nothing to do with my experience-based opinion that it's more nuanced than "dominated by liberals".