that's classical fud against unions.
incompetent employers might be good political actors in the company and make more than good employees just fine without unions.
unions just help the good, and bad, employees don't have to waste too much time every month fighting for raises.
I see this in education a lot where bad teachers that parents try to avoid end up making the same as the amazing teachers that parents beg to have. The bad teachers don't get removed so new teachers are prevented from getting a job at that school.