I think improving equality or at least reducing poverty could go a long way to towards increasing societal trust, even in the presence of cultural differences.

I think improving equality or at least reducing poverty could go a long way to towards increasing societal trust, even in the presence of cultural differences. Happier people are less angry, and thus less likely to hate the other, especially if the other has a similar quality of life to you. Not to mention economic background is a major aspect of cultural differences. Also, pockets of cultural homogeneity would be less of a concern if people still had similar opportunities regardless of which one they fit into.