That's kind of the double edged sword of unions and standardized pay scale (I've worked both union and non-union construction projects in multiple states) you insure that everyone gets paid the same for the same work, but if someone is better you can't reward them.
On one hand, the union mostly protects the workers from unfair treatment by ****** employers and should be giving the employer an employee who meets a known criteria. Theoretically if I call the hall and ask for a journeyman carpenter I should be getting an actual carpenter not someone who is a "carpenter" because he just bought all the carpenter tools from Home Depot.
The downside is that often good employees are aren't given an opportunity to excel or be compensated for just being better than their coworkers. Or if they do work harder they get sabotaged for being better (I've seen it). You also get a lot of the "It's not about the outcome, it's about the income" mindset at some point.