PS -- being responsible for nearly half a million Holocaust victims shouldn't surprise you, either. After all, this nation was founded on a rather dirtily-fought revolution, after which we actively and rather cheerfully engaged in a massive genocidal pogrom against the native population for 130 years.
Even when it came to ending slavery, it took us just over 100 years to even begin to embrace the idea.
When you look at the bigger picture of who we are, as a people, it's actually quite distressing. We're not only reluctant to accept change, but we're bloodthirsty when it comes to material gain and expansion. We're also a sharply divided people in a way that goes well beyond race, class, and creed. We're split along regional lines in a way that almost seems feudal. The more sedentary we become the more we're all starting to die at the same hospital where we were born. The result is closed communities that may be larger than a 12th century village, sure, but still behave and react in the same sort of way. You see this in how we talk about various regions (e.g. "Inside the Beltway," "The Other Coast," etc.).
Even the educated and traveled fall prey to this. Generally speaking, the London of PBS and BBC America is more familiar to an urban American than, say, Ames, Iowa.