You're suggesting that we should erect artificial barriers to prevent certain groups from accessing lucrative jobs to protect certain privileged classes from co

You're suggesting that we should erect artificial barriers to prevent certain groups from accessing lucrative jobs to protect certain privileged classes from competition. It's morally equivalent to (although more socially acceptable than), e.g., banning the hiring of non-white people or women so that white males can make more money. If you can discriminate on the basis of nationality then why not race and gender and religion also?