I share your concerns regarding the owners whose powers often go unchecked in corporate America, and I completely agree that we're reaching dangerous levels.
But I'm not speaking in hypotheticals. No, the anecdote I brought up is, in fact, the least hypothetical thing in this conversation thread. My wife examined the union pamphlet that was handed to her, decided that the union did not represent her needs adequately, but was told she'd still need to pay the union dues. This is not enabling her agency whatsoever, and actively made her conditions worse by heaping on unwanted taxes that she felt was also priced disproportionately. Yet she had no voice in this matter.
Organize a union, yes - you have my full support. Represent whichever needs your union deems to be important, yup - I'm behind it. Fight the greedy owners, great. But don't extort money from those who made the active decision to not be a part of the union. This is an active intrusion of her agency, and a real event that I brought up because I didn't think think it was fair. The fact that workers are already being exploited by greedy corporations does not excuse bad union behaviors, period.