Management and HR get frequent “trainings” about existing unions and so even if they weren’t predisposed to anti-union beliefs, they very quickly will fall in line. Management will tell them the same lies they tell workers like they can’t approve raises, can’t approve promotions, can’t help workers etc because “the union” is “in the way”. It’s hard enough to convince workers they literally are the union but management has no incentive to believe that and will do everything in their power to third party the union so unaware workers get fed up. It starts with painting organizers as troublemakers.