The economic benefits are clear - what social costs are you taking about?

The economic benefits are really not clear; at least not without caveats and clear conditions for the advanced skills that make a migrant beneficial.

This is if you believe that lower wages for high skill work is not an issue.

However high migration rates lower social trust, this is well studied.

If you take a smaller example, hiring internationally vs domestically. If you have to go domestic then you might have to settle for a less ideal qualification, requiring more training.

This is repeated everywhere, so companies that train better are more likely to succeed. Leading to conditions that encourage upskilling for locals overall.

Importing people short circuits that idea.