Nobody is specifically attacking you, and nobody is saying deadbeats don't exist on both sides. However, union deadbeats are often allowed to keep being deadbeats because the union gets them their job back if they get fired for being deadbeats.
Three guys pissed in the paint at the GM body shop after getting drunk on lunch break. When they were fired for screwing up the plant for a whole day while the paint system was cleaned, the union fought it and got them their jobs back. Does that mean the whole plant is full of deadbeats? Not on your life. I have friends who work there, and I spent a lot of time there. Lots of good folks.
If someone took a dump in a trailer, they should get canned. If someone pissed on the seat of a tractor, they should get canned. The difference between union and non is that, if caught, one will fire that driver and he'll be gone for good. The other will have him working again in a few weeks, tops. And I don't think that should be the case, first offense or not. If you're that kind of guy, figuratively speaking, I don't wanna work with you and nobody else should, either.
Nobody is calling the whole union an outfit of deadbeats. The few that are tend to stand out because they're impossible to get rid of. And they, too, taint the image of what the union offers.