Makes me wonder. Maybe they were just telling family and friends back home that they arrived safely (Did any of the flags have scribbled notes on them?)
I think they have pride in their nationalities. But doesn't that exactly prove my point. Their land is...well...back there. And here they are. What they want, what they seek after...cannot be found where they are from.
Put yourself in the place of an illegal alien. Escaping God knows what, poverty, illiteracy, joblessness, corruption, rampant violence, just wanting a decent life. The American dream. So you get to the US, maybe speak a little English, maybe not. It's natural to hold onto/long for the familar when you feel strange and inferior. Poor self esteem.
They look around, everyone else (gringos), have it easy, it's unfair. A Dutchwoman I knew some years ago emigrated to the US with her husband and children and became a US citizen. I knew her for years and every conversation we ever had began with "In Europe we did things (whatever), our way and it was so much better. We are so much smarter, wiser, blah, blah." She never got over being Dutch. But her kids were Americans. (When I asked why she'd left Holland if it was such a paradise, she admitted there was no room left. In fact, five years after they became US citizens, they went back to Holland on a visit, and their hooligan cousins threw their two daughters into a canal, calling them "Damned American whores!") I suspect this goes on in most families...the assimilation of the kids, if not the parents. Of course, with Mexico, we're talking another culture, language,and so many millions all at once. Assimilation is unlikely. My Dutch friend did learn English.