Perfectionism and the Left

I'm always amazed by the incessant demands of the Left for perfect planning, execution, and service of all of our business, commercial, governmental, safety, military, and social actions. And if we should do something very very well, they immediately fall back to the position that America isn't that good, and that our flaws make us unworthy of judgment or action.
Their litany usually starts with slavery, often goes to the American Indians, then to various environmental crimes and dropping the Bombs on Japan. There's never a mention of context, of alternatives, of the value of hindsight, or of simple human failure.  I think the greatest thing about our history is the fact that Americans set a high standard for themselves, then work hard to meet that standard after our failures. What other nation has ever set such lofty aspirations down as the intent of an entire people and their government?
Perhaps the most troubling part of the liberal perfectionist whine is the complete lack of historical context. They speak as though the miscues and failings of the United States are unique. I ask, "What country would they see as better?"
France - the first foreign nation-state to attack America; the most anti-Semitic nation in western Europe; the erstwhile overlords of Algeria, Vietnam, and a host of other continually suffering former colonies.
Britain - Let a liberal tell you how perfect Britain is, then ask about Churchill, Thatcher, the Boer War, India, monarchy, soccer hooligans, Scotland, Ireland, and then say "What?"
Belgium - read King Leopold's Ghost. What Belgium did to the Congo ranks with Nazi or Communist atrocities.
Netherlands - Really, the liberals tell me that that prostitution is inherently demeaning to women, thus the Dutch are misogynists, yes? And shall we mention the atrocities permitted by the Dutch against women and gays, in their attempt to appease the Islamists? How about we find the people who turned in Anne Frank's family to the Gestapo? And let's give them honorable mention for sending Peter Minuit and $24 worth of trinkets to get Manhattan from the Native Americans. Surely then, the Dutch bear some of our guilt toward the Indians.
Germany - say no more.
Austria - I love the way Austria portrays itself as Hitler's first victim. Just don't look at the photos of surging crowds frilling the streets to welcome the Nazis. Anti-Nazi Austrians in 1938 were about as scarce as the "Family Von Trapp" after they won the big singing festival prize.
I've traveled in all of these countries, and have many happy memories of them. But as soon as they critique America, I am quick to mention that nobody's perfect. We are a generous people, with noble aspirations and dreams. This is what makes America exceptional: We have a dream and we reach for it!