Weelll... I don't know if you've travelled in mejico and I have not since the late '70s. But when I did go there, the cities were clean, the people well groomed, life seemed very orderly and peaceful. Of course, you had the villages out off of dirt roads where they were growing corn and herding animals, etc.
Generally, public sanitation was not as good as in the U.S. and conventional wisdom was that the government, military and policia were corrupt and to be feared.
Truly, the system down there keeps them in line. I think they're fleeing that more than economic conditions. They know how to make do and life is pretty good. However, it's a status symbol to migrate to El Norte, earn U.S. dollars and wire them back to the village. Not uncommon to see the latest electronics in the most basic hovel.
Once here, they drop the conservative circumspect demeanor of life in mejico and display less attractive qualities which, judging from your locale, you are familiar with. They do have more freedom here and greed drives them more than necessity.