Yes my friend just knew a few Mexican families, who had lived in the USA for many years, and none of those were poor Mexicans (not a random, or representative sample).
Coming in illegally had been as easy as crossing the street in some of their cases. They even had some girls who lived in the USA their whole lives, but went back to Mexico to have their babies (where it is much cheaper), because they had so little concern about ever needing citizenship or legal status to live in the US.
Quite a few houses in the (nice) Texas neighborhood had Mexican owners, who were seldom in the houses, as their businesses were in Mexico, and they spent most of their time there.
Right on the border that type of back and forth used to be more common that now because there are lots of people crossing everyday and more checks for valid crossing documents.
Women crossing into Mexico to have babies is common because they say they get better care there.