Earlier quoted context omitted.
On the other hand, it's far more voluminous to catalog the list of corporations acting in bad faith and abusing their employees than finding the abuses of unions. Firing managers for egregious behavior only makes the legal case for the victims. That's also why cities don't fire bad cops, but instead keep them around until pending litigation is resolved.
If “who is worse” is a relevant metric, the question of unions would not be complex. Again, though, this is an entirely naive view of what is a very complicated reality. The very obvious reason that corporations are “worse” is simply that they have more leverage. The idea that “leverage is likely to be abused” is a much more thoughtful heuristic for the paradigm.
If you enjoy thought terminating clichés, I suppose.
Corporations, in general, have a very different set incentives and ways they can wield power and ways that people outside of their power structures can interact with them.
It's the same issue when people try to claim a corporation having the power to do X is the same as a democratic government having the same power. It's not.