One thing not being addressed here is the cost of doing business with the overly corrupt union bosses.
I'll give you an example: I was working at an auto plant in Columbia, Mo, and we supplied a Ford plant with axles. At this Ford plant there were two operators at each station. Both operators getting paid $40 per hr. One operator operates the station the full time with the exception of a bathroom break or lunch break. Then the other operator took over for those few times in the day. Both making the same amount of money but clearly not doing the same amount of work.
Another example: The Uniroyal/Goodrich plant in Tuscaloosa,Al. I was working for a communications company there and we were contracted to do some work at the plant. One of those jobs was to install a camera in the supply room because the plant was losing either $75k a month or quarter (I forget which but it was one of the two and the ain't is accurate). While we were running the wires and mounting the camera one of the supply room guys asked what we were doing and when we told him he flat out told us that it wasn't going to fly and they were going to take it to the union because they didn't want to get fired for horse playing. The union forced the plant to cover the camera between 7-3. A month or so later the workers went on strike for more money.
There are a lot of reasons for manufacturing jobs leaving this country but greed and corruption would have to be two of the higher reasons on the list.