> If these countries are really significantly worse, and that is the only factor pushing normal people to relocate, then we should be seeing massive population

> If these countries are really significantly worse, and that is the only factor pushing normal people to relocate, then we should be seeing massive population movements all the time. This is not true, because the socioeconomic status of people in a given country is not a flat line. Many Mexicans live what Americans would describe as comfortable, middle class lives. But, because Mexico is less prosperous than the U.S. per capita, there is a whole arm of the Mexican income distribution that is shifted into what Americans would recognize as extreme poverty. The Mexicans occupying this part of the income distribution are the ones leaving.