Socio-economic groups are a social reality. Even though it plays out a little differently in each society and country, prejudices exist everywhere. There is a tendency to favor certain socio-economic groups and moving from one group to another is not as easy as it seems.
If we look at the socio-economic demographics of the US, I'm sure we will see the same exact issues. Even though the distinction and prejudices among social groups may not be as problematic as in some countries, it's still an issue in our society. If one asks a billionaire about prejudice, he may claim that there is none. But if we were to ask someone residing in a low income housing in Chicago, the answer will be very different.
I'm not claiming that poor socio-economic groups are the only targets of prejudice. Those belonging to wealthy socio-economic groups may feel that they are disadvantaged as well. Take for example the sentiments of wealthy Americans about taxes.