Wealth really has nothing to do with this because it's more a culture issue than a wealth issue. Much of Europe left slavery to their colonies early in the slave trade, and poc are much less prevalent in eu as a whole, so they don't have to deal with as much prejudice or interracial/intercultural issues that many American countries deal with. Despite the cultural diversity in some western eu countries in terms of culture represented, the overall ratio of white to poc is much higher than in American countries.