It's just so easy for you, isn't it? That's what it is. Once you've made one decision, one choice, you don't ever have to think again. Pedophile? Kill him. Gang member? Kill him. Insurance fraud perpetrator? Kill him. Our system isn't perfect, and neither are we. But choosing to kill people out of some misguided sense of justice isn't the answer either. Playing judge, jury, and executioner just by pushing a button or pulling a trigger is great because you don't have to put any outside thought into it.
I won't be the first person to say that I think the world would be better off without some people. But I'm not about to start killing them. That would be far too easy.