Unions got ostracized for a reason. They in many cases evolved past reasonable worker protection. I've seen examples of both, my dad has a good union as an elevator mechanic, with strong benefit bargaining power, but which allows for advancement by merit and not only seniority.

However I worked for UPS for a few years, and teamsters is the worst organization. You can't advance by merit, only seniority, and job performance is not required to be promoted. You can't get fired except for very specific offenses like sexual harassment. No call no show.or regularly being 20 minutes late weren't cause. Made work a nightmare, with no incentive to work hard and advance. When I became a supervisor and was no longer in the union, it made running your section of the building impossible, unless you managed to trade your poor performers for others.