We can thank the wars against poverty, drugs, homelessness, and crime for this. These all serve as foils against considering ones own class and how easy it is to move downwards in America without any support for those not in abject poverty nor consideration for the disappearance of community building locations, events, and organizations, in large part due to union busting.

You are suggesting that draconian actions against drugs, homelessness and crime are causes for people associating with their own class and prejudicing other classes. I suspect it's the other way around; we are prejudiced to favor our own kind across many metrics and the consequence of that prejudice is homelessness, crime, poverty etc...

I say this because the kind of prejudice you point out is rampant across all societies, not just America and if anything, America handles it a lot better than any other society.

"America handles it a lot better than any other society."

How did you come to that conclusion? If I come up with some metrics, like the amount of support and education poor people can access, or the amount of people in jail, or access to justice, America is near the bottomn out of 'developed' nations.