Actually, they want more. We don't have any real power, as we are not a union. Some want a union because schools with unions are doing much better than we are. We've refrained hoping to work with administration. the result has been that workers have lsot jobs, lost benefits, while adminsitration ahs gotten bonuses. This doesn't sit well. But, when called up on to act, too many do nothing. Some think it is because we don't have a union, andf therefore risk being fired.
Most places where there is a union, everyone gets the benefits of the union. My wife worked at a hopsital some years ago, and when she crossed a doctor (actually saving a life by doing so), a union representive was threr even though she wasn't a member. They mad sure her rights in the negotiated contract were followed. I don;t know if you understand how difficult it is for a nurse to act against a doctor, as being right doesn't matter at all. But without that help, she'd have not done as well as she did.
So while I can't speak for all unions everywhere, I do come from a family of unions members across the country, and I hear this from them often. others benefit from their efforts without paying.
As for the propaganda, well listen to it. Most people manage to do their jobs without a lot of actual contact with problems. When they watch TV and see the constant attacks, it is only natural that people who tend to lean conservative to start with would buy into much of it. This is not to say unions are perfect. They are not. But the propaganda is a distorted view that actually harms workers when they buy into it.