I don't know of any industry where this doesn't happen. Certainly in tech there's plenty of anecdata about nepotism in hiring, no unions required.
> General complacency. Raises and promotions for the most part weren't based on performance, but rather tenure. Many people start off ambitious but end up just doing the minimum over time because there is no reward in trying too much.
Again, this doesn't differ much from non-union industry. Anecdotally (I know) almost every silicon valley tech company seems to have poor ratings in their internal polls for "we fire/retrain low performers". This isn't a problem that is unique to unions, nor can I see any evidence that it's worse in unionized workplaces.
Here's a fact about unions: Average union wages are 18% higher than non-union wages. [1]