You’ve fallen for the union’s fudged numbers. Ask yourself this: if their pay is comparable to non-union auto factories, why have a union at all? If you can get this level of total compensation at non-union jobs, then paying union dues is a waste of money, yes?
Anyway, not only are the union’s numbers fudged, but they do not factor in the “feather-bedding,” i.e. make-work policies. Requiring via union rules that a backup electrician always be present, that certain jobs can only be done by certain people, that extra people always be kept on hand, etc.
Bingo. That's what's never talked about. The absolutely unrealistic work rules that have been negotiated (read: extorted from management) by the unions are what really drives the labor costs through the roof.