It's hilarious how you write if off as nerd minutiae to expect a decent explanation for why people can't see the obvious resemblance between Superman and Clark Kent, yet you spend all this time citing nerd minutiae in all of your arguments in every thread.
If you really cared about the importance of purpose, you'd question why Superman even has to hide his identity as a mild-mannered news reporter, another aspect of the story that was left unexplained and expected for kids like you to swallow. They may have addressed it in more recent stories like UChessmaster mentioned, but for the first 40-50 years of his existence, they glossed over both questions. Superman's very calling and purpose is his story, not what villain he is currently fighting. His dual identity as Kent is also a large part of the story, yet somehow not worth a decent explanation of how he manages the most basic elements of his dual life (such as how he manages to conceal his dual identity). Batman and Spiderman comics addressed the dual identities of their characters. I guess Superman isn't worth another dimension to his character, because folks like you just want to see him lift cars and shoot laser beams from his eyes.