The two reasons you give do not hold up. First, expats in the US will be buying goods and services from Low-Paid American workers. Also, they will send a large portion of their discretionary income back to their families in the home country. Secondly, (although you use the example of Canada), most of these Visas are granted to nationals in the Far East. You state that "once the regulatory environment becomes zero-sum in such a manner, citizens of both countries gain the ability to seek out the most efficient employment, " I would suggest that that is not likely to happen in the foreseeable future.