This is a complex matter and it's hard to describe adequately in a single comment. In short, the USA has a very specific racial situation: black people had been slaves, and until quite recently (some HN readers may even remember that) there was racial segregation. The consequences of that are omnipresent today: black people are, on average, in a worse social situation than white people. One would hope that with time the situation would get better, but it's not happening at the speed one would hope. Also, for some reason people don't like to mix that much. Black-white marriages are not a norm - and it doesn't look like this is going to change soon. To add insult to injury, the children from mixed couples have another set of challenges: often they are made felt they don't belong to either community. The issue of race
does mean a lot in individual and social contexts.
Now imagine you are living in Russia. Over centuries you were a poor peasant, always at the mercy of someone. In the end you believe all your woes will end if you join others in yet another attempt to make things right, you kill the tzar, and soon you realized you just exchanged one tyrant for another. This is going on more or less until today. Nothing here has anything to do with race. It's similar in many other countries. But Americans have the tendency to perceive everything through their own context and project it onto the whole world. It makes no sense.