Yeah I'm nearing the middle of Season 2 now. Actually I think this one is kind of right wing, makes unions look corrupt and willing to defend criminals in their ranks. Kind of krazen-esque.
Given that most of the storylines are influenced by David Simon's experiences as a storied journalist, I would assume there's some basis in fact there. Not all or even a majority of unions obviously but there are certainly some that take part in some shady business, especially in old-time industries like dockworkers.