-"Light green at the front of the bus, and dark green at the back please!"
This fear is justified since people naturally view those who look, believe, and act in a similar manner as extensions of themselves. Since people are naturally selfish, they will lend aid and befriend those whom they see as similar to themselves. Conversely, since people are naturally selfish and seek to dominate others to enhance their own power, they will naturally first seek to dominate those who are different. People who are different are more likely to be seen as objects rather than fellow humans.
When confronted with these threats to social cooperation based on viewing others as objects, it is rational to foster laws, social and economic policy, and attitudes that preserve one's own kind in power. To do otherwise is to hand power over to those who will destroy one's own way of life, culture, and political system.
Political power as well as cultural and social power are zero-sum games. When one group gains in the same geographical region, other groups must lose.