The U.S.: A White, heterosexist, capitalist, Christian, educated, able-bodied patriarchy
Arguably, the U.S. historically has seemed to have been a White country, and I say "seemed" because White people have historically had the most access to societal power, and therefore has been dominant. That dominance has made White, heterosexist, capitalist, Christian, educated, able-bodied people the standard group of people in the United States, and the group is that which is judged against and primarily considered when making certain decisions. It doesn’t matter if a person who fits that description is the minority in an area; as long as they have that racial location, they will continue to see the world from that standpoint and benefit from being a part of that group. As Mohammed said, it all depends on what the "elites" say; Whites can set themselves as the standard by which other cultures and ethnicities can be applied, and if they don't match, then the others are deemed inferior.
Peggy McIntosh’s “invisible knapsack” is a good example of this. European Americans benefit from the privileges of being White oftentimes without realizing it because they hold the power over other cultures and ethnicities. The first 10 items in the knapsack include:
1. I can if I wish arrange to be in the company of people of my race most of the time.
2. I can avoid spending time with people whom I was trained to mistrust and who have learned to mistrust my kind or me.
3. If I should need to move, I can be pretty sure of renting or purchasing housing in an area which I can afford and in which I would want to live.
4. I can be pretty sure that my neighbors in such a location will be neutral or pleasant to me. (This supports the fact that the average European American lives in a neighborhood that is more than 80%, well, European American.
5. I can go shopping alone most of the time, pretty well assured that I will not be followed or harassed.
6. I can turn on the television or open to the front page of the paper and see people of my race widely represented.
7. When I am told about our national heritage or about "civilization," I am shown that people of my color made it what it is.
8. I can be sure that my children will be given curricular materials that testify to the existence of their race.
9. If I want to, I can be pretty sure of finding a publisher for this piece on white privilege.
10. I can be pretty sure of having my voice heard in a group in which I am the only member of my race.
White people currently have the power in the United States, which means they are the most comfortable and understood group in the nation, currently. Meanwhile, minority groups don’t have the privilege of being in areas where their races or cultures are the most pervasive, where they are confident their voice will be heard, and where they can speak their own language comfortably.
What can be done about this? Primarily, education about the values and histories of different ethnicities and cultures helps immensely. I know it's helped me out of my little shelter of idealism.