My father had car accidents on two different occasions. Technically, two drivers were at fault, and they both were illegals. They had no driver licenses, nor insurance. They didn't speak English, but it was not a concern for my father. He is Mexican-born. My father even gave them a note- the immigrant lawyer's phone number, and another phone number on free ESL classes. I know several friends who had car accidents with illegal immigrants.
Some illegal immigrants do speak several Indian languages, not Spanish language. Some of them do not know how to read and write a language, however they can read the symbols. It may be easy to assume that Illegals are Mexican, but some are from Guatemala, Honduras, and El Salvador.
Illegals usually live in the garages as roommates. Some housing owners in Southern CA had removed a half front yard or a whole front yard to place the cement to make space for another vehicle to park. In Southern CA, and AZ, they do live in camps in rural areas. Some of them do live near a river or a pond as a source of water.
I recall New Mexico is one of the several states that permit Illegals to receive their licenses a few years ago to alleviate that familiar problem.
I personally know some well educated illegals, including UK immigrant, The problem with immigration laws I believe need to be updated, because they're short-term, and did not give them enough time to do what they have to do in order to live legally.