There are good business people in these countries you may, at least on the surface, despise. If a few of them want to raise chickens in their backyard or rebuild engines on their kitchen tables I have no problem with that (within reason).
If there were a way to equitably equalize the disparities evidenced in Mexican and (less pronouncedly) Canadian economic practices, then there is little reason to discourage a more transparent relationship between the three. The natural resources north and south of us are incredible, and the people on either side are, by and large, not nearly as stupid as liberal Democrats.
There is. Competition.
If the populations of these countries refuse to rise up and demand freedom from control freaks, they don't deserve it.
At least, that's what Ben Franklin said about certain colonists.