That by not being ridiculously overtly bigoted, they have actually interrogated and rejected their own bigotry. The former is basic and mostly relies on social conditioning. The latter requires reading history and people who are criticizing things with which you may identify and therefore take very personally. The latter is not taught in school and school does not provide the tools (outside of literacy) to do so, so it’s a difficult, painful, abd regrettably rare thing to see, usually requiring sone trauma to change.