So, I'm looking at the list of "16 Worst Things (the writers have had) the Joker has ever done", and I can't stop thinking, in-story, why is that guy still alive? Why doesn't Jason Todd kill him, or Wild Dog or any of those other vigilanties that kill. Why doesn't Maxwell Lord or Luthor kill him? Or the Spectre? Or any of the Gotham mobsters? Why does Batman leave him alive?