When I was in school, history was taught from a US-based Western Civilizations perspective (where whatever US did == good, even when it wasn't). We did cover WWII and Nazi genocide, but the main topic was the US role in the war and what happened inside the country.

In particular, we glossed over most of what US did to its Native ("American Indian" was the term at the time) population and what the US did to its Black population.

I think part of that is that we got most of our history when we were too young to delve into such things. In high school, we had one year of US history (where we did cover such things in more detail) and one year of US government (where we covered the ways those things helped the nation evolve into its then-current form).

My high school US history / US government instructor was an immigrant from Eastern Europe. He had been a small child during WWII, but could recall hearing Hitler's voice on the radio. So he could dispassionately cover the Japanese-Americans' "internment" while comparing it to similar acts in other nations at the time. The occasional first-hand observation was very interesting.

Other than high school, most of our history was taught in 3rd grade (California history), 4th, 5th, 6th grade (all other history); with other years just being repetition of the same stuff. 7th grade was interesting, because the initial history teacher was from Massachusetts and dug deeply into the Boston area's Revolutionary War history. She became ill and we got merged into the other history class, where they were talking about Egypt.

The other thing I should mention is that throughout my school years, history was part of an uninteresting mish-mash called social studies. So we'd look at history and try to throw in a little political science, a little bit of archeology, a little bit of psychology and sociology, a little bit of economics. I guess it was supposed to enrich our learning, but it made social studies one of my most hated subjects until high school, when each subtopic had its own class. Most of those subtopics are interesting on their own, but stirred together in a community pot, they're watery and flavorless soup.