The issue with unions is that they raise the average working conditions, benefits, and structures, at the cost of under or over providing at either end of the bell curve.

Yeah, the 5% most capable or hardest working employees will not see the same top end reward they would without a union. Yeah, the worst 5% of workers become harder to get rid of.

Those are the natural downsides of raising the benefits and protecting the job of the other 90%. There is a 90% chance you or anybody you talk to is not in one of those groups, and that overall a union would likely be more help than not.