Talk to a few more southerners who have watched non-union manufacturing be utterly decimated, and you'll understand that a lack of unionization didn't keep those manufacturers here, either. If anything, the few union plants hung on a little longer.
Perhaps you can then explain how a union actually HELPS a manufacturer - I can’t for the life of me see how work rules, (very) narrow work definitions, brainwashing workers to HATE their company and especially its management, and labor strikes actually HELP manufacturers, but maybe I’m missing something.