Yes, because there is no trust between management and union. They should have the union hire managers as well, and simply mandate key performance indicators for safety, cost and so on.
All these people joined for basically the same reasons and they all had the same training but the huge differences in job satisfaction says to me, the problem is at the top. Unions become militant for a reason and when that union is in house and not part of a bigger entity, you have to look hard at management.