Every industry has good and bad workplaces, with good and bad cultures. Maybe 30 years ago it was a fine workplace and then two of the curmudgeons joined, drove out a lot of people who weren't curmudgeons, and 30 years later you've ended up with a bad culture filled with curmudgeons.

I don't know anything about teaching in the US, but I don't think one experience like that really says much about the industry as a whole: it just says something about that particular workplace.