You're right - unions don't do that. They could be incorrectly perceived as doing that though, which is the comparison I'm making to "Americans love feeling like they're about to be rich". That's very clearly not how Americans feel and framing it that way is pure propaganda, as you put it.
You might want to look into the practices of police unions. The inability to fire for bad behavior is part of why police forces turn into self serving monstrosities.