The problem with suggesting that the salary bar be set at the median of the lifetime salary, is that it does mean closing the door to current international students in the U.S., and to recent graduates recruited from universities abroad. The minimum bar for an immigrant should not be that they are better than half the people already employed here in their field, regardless of their stage in life. And, of course, most…
The government of a country should be first and foremost advocates for, and protectors of, the welfare of its own citizens. If a large number of those citizens are being encouraged to accumulate massive debts gaining an education that them leaves them unable to find a job, then that is a social problem that needs a solution. And if the government can help the situation by putting reasonable restrictions on the number of foreign workers competing for those jobs, then they absolutely should do that.
I really do not understand how so many people came to view these kind of theoretical, free-market niceties as more important than the practical wellbeing of their fellow citizens, but it's an incredibly dangerous attitude. If you support free-markets and globalisation, then you should want them implemented in a way that doesn't cause major social damage that ends up creating hostility to them. Otherwise, you end up with the kinds of populist movements we're seeing now, which feed upon the resentments of people who've watched successive governments refuse to place their own citizen's welfare above that of an ideology that harms them.