Batman's one rule is a massive flaw in the Dark Knight trilogy

Please note I've never read the comics.

There's debate over what his one rule actually is. Some people say it's that he won't kill. Some people say it's that he won't be an executioner. The truth is, it's never explained. In Batman Begins, he says he won't be an executioner, but he never says that's his one rule. In The Dark Knight Rises, he says "no killing", but again he never says that's his one rule. In The Dark Knight, he says he has one rule, but he never says what it is.

If his one rule is that he won't kill, he breaks it quite a few times. He killed multiple people when he blew up the League of Shadows, he refused to save Ra's al Ghul, which is pretty much the same as killing him, he killed Two-Face by pushing him off the roof, and he killed Talia by shooting the Tumbler.

If his one rule is that he won't be an executioner, it's pretty stupid that they made a big deal out of it. With the exception of anti-heroes like Deadpool, all superheroes have that rule, they just never think about it. All superheroes never kill unless they have no choice, except in extreme circumstances, such as Hawkeye murdering people after going crazy with grief in Endgame. It would be like saying "I will never rape anyone". People would say "I never thought you would, why did you feel the need to say that?"

Also, him refusing to save Ra's al Ghul really did feel like an execution.

The biggest flaw is that this wasn't addressed. For example, someone like Alfred should've actually questioned him on the fact that he has a one rule but doesn't seem to care about breaking it.