Yes they do. Step one is employees forming a union. Step two is negotiating a labor contract. If an employer says no to a labor contract and fires everyone, th

Yes they do. Step one is employees forming a union. Step two is negotiating a labor contract. If an employer says no to a labor contract and fires everyone, the employees are back at square one. Back in the day if a union tried to fire everyone and rehire, the union would physically assault scab workers and their families. Hence the close ties between unions and organized crime. (EDIT: I added this part to point out unions do not have any leverage anymore to work with, sorry if you misunderstood it as implying unions still regularly employ violence)