I'm in a grocery union now and things are pretty horrible. There are so many workers that got into the union for whatever reason who refuse to do anything other than the bare minimum. This causes everyone else who is a decent person to pick up their slack, yet get paid the same as them for the most part.
It also hurts the company in the long run. Causes overtime to go way up. You pay these people who under any other circumstances would not have a job to do a piss poor effort. Then you gotta pay people overtime to finish what they couldn't. It seems near impossible to get them fired and the union loves catering to them.
Not to mention it brings the morale way down. There are so many people that tell other union workers to stop working so hard because it's making them look bad. Often other people see how little of an effort they make and wonder why the hell they have to do so much if this person doesn't have to do anything. Nothing is more frustrating than going into work, busting your ass and watching the drunk do nothing and justifying it with "I get paid by the hour, not the quality of work."