Maybe that's because they had. Idk. Slavery. And racial segregation until not too long ago.
We still have racial segregation. It's just not blatantly codified in law.
You can't stop black people from voting, for example, by making a law that says "Black people cannot vote."
But you
can deliberately make it harder for black people through gerrymandering (drawing voting districts in such a way that the results are skewed towards a certain party without actually changing the number of votes), regulations that make it harder for black people to vote by limiting the places and voting times, changing the information we need to register to vote, legally-skirting voter intimidation, and other forms of disenfranchisement.
Apply this kind of racially-targeted bureaucratic maneuvering to
everything in society- housing and property ownership, job searching and entrepreneurship, education, drug laws, etc., and you have a society that is thoroughly unequal between black people and white people without many laws on the books blatantly declaring so. But because there isn't a law that literally says "Black people cannot do x," white Americans and foreigners make the mistake of just thinking that equality has been achieved in America, and thus the equivalence of black communing to outright fucking white power happens inevitably happens when black people say they like temporarily escaping the confines of this unjust society through camaraderie and fellowship with the people who know exactly what they're going through.
And then I have to roll my eyes, write posts like these, and retreat into my current anime just to make myself feel better. I'm currently watching Hajime no Ippo and it's fantastic.