We specifically avoid most union work for the jobs we do because it tends to A) Take too long to get the job done, B) Most guys we've worked with tend to find problems rather than solve problems, and C) They cost too much, especially when they are taking longer at higher wages...
In a lot of cases we'll hire plumbers and electricians who are union, but do the work as non-union. Even these guys see the issue with having to pay a guy per floor to stand around with a broom all day "sweeping" on a construction site. (not kidding, it's a union rule in NYC)
I've got nothing against Unions per se, but the attitude and entitlement of a lot of Union workers will be their downfall. Show me in practice that Union work is a superior product (whether it is more efficient, or higher quality) and we'd likely be willing to pay the additional cost.
My wife is in a teacher's union, and my brother is in the autoworker's union. Both of them mention the issues they have with the lazy guys who have "put in their dues" and take advantage of their tenure & seniority. If unions self regulated to get rid of these people (who give Unions a bad name), there would be way, way less criticism directed their way. Unions need to be on the same page with businesses/school districts in some areas. Some protection of senior members is needed, but those members also need to earn their keep, using their wealth of experience and knowledge to help produce/educate, rather than scam the system.
Again, my wife and my brother make good money because the unions exist. However, when you place seniority above all else, you're asking for a steady decline in production/quality of teaching. It sucks that a guy who works his butt off at a cheaper rate has to get laid off while the old guy who gets 6 weeks of vacation and spends most of his day trying to look busy while accomplishing nothing keeps his job...