The Texas colonias are inhabited by people who crossed into the US from Mexico. There are many Americans citizens there because everyone born in the US is automatically a citizen. But their standard of living says nothing about the accuracy of the statistics addressing the standard of living at the 20th percentile. (That’s 60 million people from the bottom.)

That’s not to say we shouldn’t “do something” about their living condition, just that your post is a non-sequitor. When Sweden accepted hundreds of thousands of refugees, the median income of the country almost certainly went down. But that doesn’t mean everyone became poorer.