Yeah, I don't think racial diversity counts for the trust issue. Obviously there are some people that won't trust someone based on their race, but it seems like most groups are willing to accept anyone as long as they follow cultural norms; skin color just seems to be a quick proxy for "they look different, so they're probably culturally different". Just watch the aftermath of a local football team winning a big game. It doesn't matter if you're rich or poor, black or white, everyone in the city celebrates together.