My father was a teacher, and a union member, and I can tell you from personal experience that management will be more than happy to fuck people over if they think they can get away with it, or if it will make there lives easier. In my father's case, it was a student accusations that put my father in the cross hairs. Luckily, my father had the support of the union, and showed it was a false claim because of students poor grades. Not that the parents or administrators cared without the rules and protection from the union.
The union also helps keep wages up, something few business would do voluntary. At my current job I wouldnt union representation considering how much unpaid overtime we all do during tax season. I feel like businesses have for decades been eroding the very idea of the 40 hour work week in favor of unpaid overtime, and other assaults on the employees.
Anyway, the European Union model has been shown to much more effective, so there is a third way. I just feel that with Trump in charge, and unions being broken, we are getting real close to a 1980s sci Fi movie, with corporate overlords. Although we might get mad Max or Terminator instead. That's the nice thing about Trump, any 1980s sci Fi movie could end up being true.