The core of the problem being that they see themselves as being, individually, non- and indeed anti-racist -after all, they're interacting with a PoC, arent they? To shoulder the responsibility for eliminating White Supremacy is to admit, inter alia, a responsibility to and for other White people, as well as to and for PoC, to bring about change.
But this involves a recognition of collective responsibility and the need for collective action. White America, and post-Thatcher Britain, has been taught to view collectivism, mutual support and shared responsibility as one and the same thing as Socialism or Communism -the Enemy.
A nasty Catch-22 in which, in order to help the Other, they must themselves become Other, and in fact Enemy, to the society they live in.
Some are prepared to accept that in the name of a principle, too many others are not. Until that changes, we just have to keep buggering on.