Legally it is very hard for a Mexican to move to the Midwest. As in almost impossible requiring almost 20years.

I am not Mexican but it toke my family 14 years to be able to move to the US from Palestine, although my grandparents and uncles have been here since the 80s. It really isn't hard.

A company doesn't need to move everything, they can just literally build a new factory or rent one else where, not only that they would even get tax breaks as incentives for moving.

Borders enforce the huge discrimination in pay between TJ and San Diego. Even though the same companies work on both sides of the border.