The free mobility of labor is incompatible with the welfare state if every person who is physically present in a location to perform an economic service automatically comes into the same set of welfare benefits as a local. That needn’t be the case.
This is what liberal democracies find hard. But it’s not impossible. You have to confront the injustice of the world and say this person is better off even without the welfare benefits, and this process is good for the world.
Harvardekonomen Lant Pritchett, om friare migration som den bästa utvecklingspolitiken, i Reason.