It’s not a guarantee that collective bargaining will help privileged workers, and union dues aren’t free. The statement is a bit cheerleadery, but isn’t necessarily irrational.
Yeah, I used to work at a company with a mix of union and non-union sites, and the unions were good in a sense that the company standardized a lot of general union policies across sites. So the end result was the non-union sites had most of the pros of a union and none of the fees.