I don't understand why this would matter. Why would homogeneity of the population have anything to do with how many people the police kill of the privileged race? Does the existence of black people in America increase the number of whites killed by police?
When we compare crime and such between USA and Europe you always say "But USA is so diverse!", isn't that racism? I mean, you are basically saying that you have to live with crime, murder and such when you have a diverse population. Or do I misunderstand you?
There was a study recently produced that showed that simply installing street lights in a neighborhood reduced crime dramatically, when you take into consideration that installation would be funded by local property taxes, and that majority minority neighborhoods have lower property values, partly due to post war discriminatory housing policy, it is clear that there is somewhat of a self fulfilling cycle here.
So it's completely natural that a country as diverse as America would automatically balkanize itself along class, national, and racial lines.
Note that studies have confirmed this: https://en.wikipedia.org/wiki/Robert_D._Putnam#Diversity_and...
Certainly ethnicity is a fluid concept. The language, value system, and cultural context of a Texan may differ from that of a Minnesotan. However, I think we can agree that your average Texan or Minnesotan will likely have a greater common understanding if paired together than with your average Swiss or German person.
Because conscripted labor was an independent tradition going back thousands of years. Compare the legal status of compelling people to work on the roads.
There was also an exception for the military, though that wasn't written into the 13th amendment.