It sounds like you're confusing what they do currently and what the system should be set up to encourage instead. That things are broken right now is not a valid argument in favor of the status quo. The point you make only proves why it is so important that unions should have as much economic power as corporations do, so that the buy and sell sides of the labor market have negotiation parity.

I'm being descriptive, bot prescriptive: I'm stating what the priorities are under a capitalist system without the rose-colored glasses offered by the Just-world fallacy.