First, Gravity can be defied by thrust. Other factors do exist. My whole point was that discrimination exists whether we want it to or not. Whether anyone actually does it on purpose, or not. It is a permanent fixture for our entire species and it could be a mistake to not account for it. Even if we all looked the same, we'd find something else.
Second, are you sure your conclusion is accurate? Hitler did a number on the Jewish population. Anti-Semites do exist. And there are factors that provide what one might call... privilege. It could be that many such folks arrive from wealthy families. But not everyone does. I would say that other factors muddy the results, and can skew our perceptions, but the sort of discrimination I spoke of is simply inherent. If you'd like to argue whether it exists at all, I'd say look at city neighborhoods, and ethnic enclaves. People grouping together based on familiarity is a universal factor that is readily demonstrable.