I heard anti-union rhetoric in college when people were wondering why it cost so much to set up A/V in a lecture hall. If you haven't heard any, I'm not sure whether to tell you that you've lived a sheltered life or you've so internalized the anti-union rhetoric (like
your comment, right here!) that it doesn't register when you hear it.
Also, I'm very confused about your "liberal areas" comment. My impression as a regular NYC subway rider is that the subway doesn't have massive funding, and what little funding it has is being spent poorly because of decisions by politicians, not because any union has asked for anything or is getting paid too much. I've heard a lot of anger at service cuts, at our governor, at the recent fare enforcement crackdown. I've heard zero anger about the salaries paid to unionized employees.
(I have, in fairness, heard the fairly inside-baseball complaint that the unions are pushing back against extending one-person operation to more train lines, for fears of more job cuts. I don't know anyone who thinks that's the biggest problem facing the subway, and I think the vast majority of the ridership, even the politically-active ridership with opinions about the merits of unions, has very little idea that this debate even exists.)
I do agree that people in liberal areas are unhappy about police unions. I think that's its own, special thing (among other things, in NYC the Second Amendment applies more to cops and retired cops than it does to civilians), and I don't get the sense that people are unhappy about teachers' unions in the same way.