Like importing goods, importing people does cause reallocations - Mahalanobis

But it is an elementary mistake to think this necessarily adds or subtracts from aggregate output per capita. As most politicians fear being labeled 'anti-immigrant' because it is considered tinged with racism by journalists both right and left, there is little attention paid to this issue, even though referendums strengthing laws against illegal immigrants regularly pass with large majorities and no party sponsorship. The non-PC answer rarely discussed is that yes, immigrants can add to growth of a country (per capita), but only if they have certain complimentary or exceptional skills.