As someone alluded to before, my experiences with unions (and yes I have been in one) is that their biggest detriment is the blind protection of what we'll call "less than desirable" workers. The vast majority of workers put in an honest days work, but you can't underestimate the damage the bottom 5% or so can do. Also, it's been my experience that most of the stewards knew that that the person should be canned, but felt their hands were tied because "he pays his dues."