As a humanist you may not like that. As an American, I believe that's right. Stop dragging the wage base down because it's "humanitarian" for immigrants. It's not. It's just enabling abusive labor practices.
Mexico's wages will rise just the same as China's as they industrialize.
Plus, some of the Americans who take over Mexican jobs may not have them for long. If businesses can no longer obtain low cost labor within the country, then where possible, producers will relocate south of the border, or elsewhere, or increase mechanization efforts to decrease their costs. And where not possible, they may be priced out of the international market as the production cost of their goods shoots up.
Mexico is already industrialized. Also, the same nationalist position that opposes immigration also supports erecting trade barriers that prevent goods manufactured abroad from being competitive.
Edit: you industrialize with domestic demand. That's not a sham. That's economic stability.
I don't care the color of your skin, I expect you to follow the same rules everyone does to apply for citizenship.
That's how sovereignty works. Or are you advocating for removal of sovereignty for the economic benefit of citizens of other countries because "that's more moral"? Hardly.
EDIT: In reply to your edit, I have no idea why you'd bring up "removal of sovereignty". I don't see anyone here even hinting at that.
To take a modern example, will Maharashtra's proposed law against Biharis driving autos be moral if it has popular support? (Background: Marathi nationalists have - this year - proposed Jim Crow type laws against non Marathis driving taxis/auto rickshaws.)
Whatever the law, some people will always be breaking it. Should we wait for murders to stop happening before we reform the laws regarding it? We'd still have crucifixions and stonings! That doesn't mean one supports murders, just that it's not a justification for inaction.