Please bear with me. Prose is not my best skill. If you like to read anthropology, you probably know that there is a cultural level in which people live as isolated individuals or in single family groups. At this level, the commonest cause of death is murder. This is not prejudice; it's well documented. Tribes and villages evolve crisis resolution customs that keep them from destroying themselves. But a man who has only seen 3 or 4 strangers in his life will not look upon them as sources of news and entertainment; he will will see them as dangerous creatures that must be closely watched and killed if they do something unexpected.

Our western world is not like that, quite. However, under the influence of adrenalin, I think that a stranger - looking different, dressed differently, speaking differently, smelling different may often be seen an a threat rather than as another person. This helps explain why the level of violence is so much lower in homogenous cultures; there's less strangeness to adapt to.