The quiet part is that people in a country with abundant natural resources don't want to have to share them with people from other places with fucked up situations. They want a walled garden because they think they can tend it well enough on their own to not be surrounded by extra burden. Who needs to compete when there's enough to go around here?
If we were rational ourselves, we would bring our freedom to the countries who's people are fleeing to us for refuge. Mexicans have it so bad that they're running to us? Well clearly we're doing it better than Mexico, so let's clap their leadership and show them what's good, right? I mean fuck. It's better rationale for a war than trying to control some other place for is oil and pretending that's not the case.
Idk if there's oil in Mexico. The point I'm trying to make is that we're 'liberating' under false pretenses and not doing it where that would at least make a little bit of sense.