I think we're roughly in agreement. Businesses are composed of the capital providers, the organizers (who decide how to deploy the capital), and the workers.
Capital providers colluding to set a loan rate is illegal. We shouldn't allow them to collude legally; they are a small number of experienced actors operating with information asymmetry already.
Organizers (i.e. senior management) colluding is--I don't know the legality--just unnecessary. They often are paid based on value add (equity, bonuses, etc.), so they are already reasonably aligned and need no further protection.
Workers can exist and do exist with or without collusion (i.e. unions). As a society, we've reasonably decided that colluding is legal, because workers often add a lot of value but have individual low value-over-replacement (hard to organize because of numbers, often inexperienced, etc.). Unions exist to help raise individual value-over-replacement closer to value-add.
What's being discussed here is the pluses and minuses of unionization. What I disagree with is people in this thread--not specifically you--comparing the collusion of workers to the existence of capital or organization (i.e. corporations are sometimes bad! why doesn't anyone discuss that!).
First, obviously people complain about corporations all the time. But second, private companies (capital and organization and workers) add value, and no society has done well without a large component of this.
There are many pluses to unions. But, especially as currently implemented, the minuses exist too, including that many of them focus on raising VOR but wholly ignore value-add, in a way that forces the business into slower and poorer decisions; or shielding some workers from the consequences of adding little to no value.