When everyone is the same (genetics, background, culture, etc) there is very little structural inequality in a competitive market. In an empire like the US, so

When everyone is the same (genetics, background, culture, etc) there is very little structural inequality in a competitive market. In an empire like the US, so many groups exist in a hierarchy that government support is required. In such an environment bare competition simply reveals and highlights fundamental difference, which is not conducive to social cohesion or harmony.