I would challenge that. North America, because of recent (post-WWII) immigration, has larger diversity and multiculturalism than any place in South America. read more
Of course, this also led to one of the largest diasporas in the world, the Italian one, to come to South America by the millions. So my answer would be that the religious and cultural formation of South American peoples are an incentive to multiracial coexistence in a way North America never experienced. Race traditionally isn’t that big of a deal. read more