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.