What's ironic is that these body shops are mostly non-American companies (usually Indian ones that hire Indians).
If you're being outcompeted by the incompetent body shop employees, you need to step up your game rather than try to restrict the labor market.
The proper framing is that their visa can be held over their head to extract 14 hour days 6 or 7 days a week and other working conditions and salaries that Americans would not accept or be able to compete with (for good reason).