Excuse me? Please don't put words in my mouth; I did not say "people in Mexico just fundamentally care more for their families than people in the US do." I said the
culture is more family oriented. You can certainly care about your family deeply and not have a culture of living together and financially supporting one and another/pooling resources. Caring is not the same thing as resource pooling. You may be willing to jump in front of a bus for your sister but not come from a culture where it's normal for you to live with your sister into adulthood. It's simply different cultural expectations/norms than we typically see in the US.
This culture may have come about from a practical standpoint out of need, or maybe not. It's certainly worth noting that even if the culture wasn't such it's certainly practical for maquiladora workers to pool family resources due to low pay.
And yes, um, certainly parts of the US that have a large Mexican-American population would have a more Mexican-American culture.
http://www.livescience.com/38647-mexican-culture.html
>Mexicans put a high value on hierarchy and structure in business and family matters. Especially outside of cities, families are typically large and Mexicans are very conscious of their responsibilities to immediate family members and extended family such as cousins and even close friends.