The problem is that it’s a slippery slope. Batman doesn’t want to be the type of person who kills; that’s the line he’s drawn in the sand, for better or worse. If you justify killing just the Joker, what about the next supervillain that shows up? And the next one? Suddenly you’re just killing every one of them, because it’s easier

Plus there would be a lot more public scrutiny. He gets away with a lot of shit I think partly because he doesn’t actually kill anyone. The police actually mostly work with him not against him; I think that would change if he has a huge body count