>>211372158
It no longer works in the comics either. Batman has characters like Red Hood and the current Robin work with him regularly even though they have killed indiscriminately in the past and belong in jail. But they are both his sons so they get a pass. Same with Catwoman, preferrential treatment because they are an item despite her murderous past.
Also, not to get too nerdy on you but during Morrison's run, Batman tracked down the guy who killed his parents and deliberately drove him to commit suicide with the same weapon he used on the Waynes. That story was cannon for many years until a couple of reboots happened, no idea what passes for continuity right now. The issue in question was published as early as 2008 or thereabouts.
And if you go way back to the origins of the characters, both him and Superman would kill if necessary and not dwell on it too much. The comic book code of the 50s and 60s introduced the no-kill nonsense, messing things up and cartoonifying the entire DC universe in the process.

Tl;dr: the no-kill rule is dumb in the comics as well but too many stories have been built on it to abolish it now