Your point about the pervasiveness of American denial is well taken. But we are not alone, unfortunately.

I do not know of a single nation in the world, (with the possible exception of Bhutan) that is NOT in denial about the skeletons in their closet, past and present. Denial and tribalism (i.e. total identification with one's own nation, religion, or "people") go hand in hand. And unfortunately, tribalism is as innate to humans as it is to chimpanzees or other social animals. It CAN be transcended, but only by individuals with the ethical grounding, intelligence, and will to make the effort, not by a nation in the aggregate, I'm afraid...