I think you got that exactly wrong if flawed means evil.
I recall one of the founders of this nation saying that to construct a government based on the premise of honesty and altruism of its officials would be "calculating on the weaker springs of human nature."
That they constructed a Constitution that did not fall into that trap, one which took into account the fact that people can't be relied upon to be honest and altruistic, is why it has become the longest-enduring such document in history.
I think you got that exactly wrong if flawed means evil.
Okay, surely you sometimes feel dark impulses that you choose not to act on? That's what I'm talking about: an inward bent to evil. Some people wallow in it, others spend their lives resisting it, but for all of us it's there.
As you noted, most people will indeed make reasonably good lives for themselves if left alone by criminals and government -- but -- criminals by definition wallow in evil and governments all too often attract the same type of person (only less brave.) Liberals tend to believe that crime is somehow externally caused (again, because they believe in man's basic goodness) and though they may cry out against the sins of government (real or imagined), they deep down believe that a truly good government is actually possible and keep trying to build it.