Holocaust happened here and was done mainly by western country. It was very much result of western ideologies. It was also successor of history of pogroms and antisemitism that existed in Europe. Europe still have some of people who did lived through it. The movements that made holocaust happen and their ideologies still exist and are alive in Europe and in western countries.

America is quite close culturally, literally fought in that war, literally fought a lot in that war because Germany was threat to America too. America did not had just few units in WWII, it was major player.

It would not be surprising for history of "us" and politics of "us" be more prominent in western countries then history that happens in different countries. Afaik, in Cambodia, they do talk about their genocide and have museums of it.