I think we need to take into consideration that the author is young. She is assumes that all "white people" live in homogeneously "white" neighborhoods, towns, and cities, and for affluent "white people", regardless of their political orientation, that is correct. Money buys security, and whether you live on the Hillside, Turnagain, or South Anchorage, security means distance from poor people, and many, but not all, poor people have a lot of melanin in their skin. And, because all the media is dominated by affluent "white people" who create in movies and television almost entirely a "white world", of course most people believe this. Even when traveling anywhere in the world, around the world the affluent can afford to keep their "bubble" of superiority. There is an well-known correlation between racial segregation and progressiveness. Seattle, Portland, and many other progressive cities and towns are, in fact, overwhelmingly "white".