You are not only right, but NAFTA plus was implicit in the agreement from the beginning. The object was to create one North American economic zone, and that implies the free movement of labor across borders (the same problem that plagues the European Union.) Ross Perot's "giant sucking sound" really meant that we would suck into the United States the vast Mexican peasantry, unemployed at home, uneducated, and resistant to assimilation. When decisions are made for entirely economic reasons without regard for social consequences you are buying trouble. The trouble with NAFTA is just beginning.