It being a common practice isn't relevant to whether it is best for this industry and its workers. I'm not saying I disagree, but your reasoning just doesn't support your argument
But that's my assessment and I'm probably abnormal in my situation. I'm happy to be wrong though. If more companies form unions and these companies pay better, reward good performance more fairly, have less intrinsic bias, etc, then I'll be the first to jump ship.
So it's you who seem to be without arguments.