Lex represents all the potential of humanity. He's an intelligent, confident, self made man. All the power he possesses, he worked for.

Superman is an alien child of infinite power. But he did nothing to earn that power. He's a manchild, who deceives the world he claims to "protect" by adopting a disguise. When he's not doing that, he's forcing his values on the world with force. And by doing that, he stops all progress. Superman is afraid of anything out of the ordinary, anything that could rival his power, anything that could take him and his backwards regime out of control.

Superman is a self appointed king in a world that doesn't need one.