The situation around conventions is particularly bad. The nickel and dime-ing of the venues are part of it but, as you say, many of the work rules are pretty stereotypically outrageous. Not that everything is entirely unreasonable; at convention center scale, things would descend into chaos rapidly if booth staff and others started winging things. But it's pretty bad especially in places like NYC.

It's not universally bad but, as someone else said, organizations become about themselves and their leadership. A former GF was in a union and she had very few good things to say about hers. [ADDED: That is an anecdote. I state no opinion about unions generally.]