The Joker is physically a normal human being. He gets out of prison due to manipulation, not because he punches through steel and concrete. So again, it's not Batman's position, right, or responsibility to execute him.

And you believe they exist in significant numbers.

The Jeffrey Dahmers and John Wayne Gacies of the world are extremely rare.

Far more common are the gypsy cops police officers who kill, are covered by internal affairs until evidence goes public and then lose their job... until they're hired in a new precinct. Derek Chauvin was the exception because we had nationwide protests to which the federal government reacted badly. Meanwhile our ICE troopers are acting like fucking Sicherheitsdienst (and I hope some decade nazi hunters go after them for their crimes against humanity.)

But the real damage comes from the Gates and Bezoses and Musks in the world. The Koch brothers may have singlehandedly killed us all by instilling doubt in a climate problem we've known about since WWI, and deferring global response so that we're still not doing enough a century later, when the world is literally on fire. All the serial killers and gang lords and street purse snatchers and whatever else is represented by Frank Miller's mutant overlord do anything compared to Purdue Pharmacy and the Sacklers. Or DuPont chemical poisoning the global water supply with PFOA.

And yes, they kill and kill and kill but they also control the entities that control the justice system. Kinda like ~~Jeff Bezos~~ Lex Luthor.