Very simple: the Wall prevents some Mexicans from working for willing employers who would pay them a wage above the poverty level.

I'm not claiming that Mexico is a middle income country solely because of US immigration restrictions - far from it. Pointing out their trade opportunities would be a valid counterpoint to that claim. I think most of Mexico's economic problems are entirely self inflicted (same as for the US, Venezuela, or most other countries).

The Wall doesn't even prevent Mexicans from working for a US employer. Any willing employer can invest in Mexico.

And if Mexico's economic problems are self-inflicted then it makes perfect sense not to invite people who inflict such problems.

From what I can tell, the vast majority of harms that Mexicans inflict is done at the ballot box rather than the workplace.

Note that I never advocated allowing Mexicans to vote; on the contrary, I'd like to disenfranchise bad American voters rather than enfranchising bad Mexican ones.

Among many ideas for improving democracy, disenfranchisement is probably the one most often tried and history clearly shows that it's unmaintainable. Sooner or later it always gives in and nearly everyone gets to vote. In modern US it will be sooner.

There's simply no realistic path where people move into a large, modern European* country and remain second class residents with limited influence over the government. This state won't last a single generation.

* USA included by heritage if not by geography

> This state won't last a single generation.

Well yeah, of course their kids would get to vote.