Not true. Was in and out of UAW plants for years where the stewards made their own rules day in and day out. Granted there was a framework in the contract, but the "interpretation" was up to the union, and they twisted it every chance they got. If the company didn't like it, the union would slowdown, or sabotage equipment, (they did it to mine), or some other little trick. This petty stuff never made the news, but it happened.