There are county zoning laws against manufacturing, even tiny manufacturing by individual men in tiny shops, in the middle of nowhere with nearly no population. Over-regulation has much to do with it. One interesting thing about it, is the strangers who’ve shown in county commissioners’ meetings around the country over the years to stop small production businesses from starting under environmentalist pretenses—some of them even known associates/relatives of managers of much larger global businesses.
While that might have some impact on new small start-ups. It doesn't explain the vast marjority of off-shoring. Those businesses were already zoned. They didn't leave the country because of zoning.