I've worked in Worldwide Operations Strategy for a major unionized manufacturing company. I've done colossal projects looking at whether to shift capacity to Germany, the Northern USA, the Southern USA, India, Mexico, etc. There's a reason why Germans get the wages they do and Southern Americans get the wages they do.
German line workers generally have years of technical training on and outside the job before they get those wages. To make a comparison, German Technician to German Engineer is a bit like Nurse to Physician. They know their stuff. You can hand them 1 page of tech specs and they can figure out how to assemble it and make dramatic improvements to line efficiency. We did an experiment handing the assembly documents to American workers and it took a TON of engineering time to get them up to speed.
I do no exaggerate when I say that the hardest thing we have in the US South is hiring enough functionally literate employees. 75% of applicants recently were functionally illiterate. The ones we do hire want to spend about half their workday chatting. This is in multiple locations (Tennessee, NC, Mississippi). This BS about Americans being great workers is no true. Some are, some are not. Guys in Wisconsin and MI typically know their stuff but have terrible attitudes. Guys in the South know next to nothing and have bad attitudes.
I have tremendous respect for union employees. They do great things, and I'm more than happy to pay for productivity. This is NOT what union leaders want. They value solidarity above all else. They feel that as soon as management can divide and conquer employees by separating the good ones from the bad ones, the union leaders will no longer be necessary and they'll be out of a job.
The teachers union will fight tooth and nail to prevent evaluations of teachers, regardless of effectiveness. Despite the fact that Math is Math and kids are kids (for the most part), the teachers union management LOVES the system that locks teachers into a lifetime at one school system. They fear the concept that good teachers could bounce around seeking their own better wages through an efficienct market system because it completely short circuits their x% of the wages.