Still about capital punishment (sorry about breaking the gun topic)
Let's play a little thought experiment. Let's say there is this hypothetical country where the punishment for murder is death, and restraining laws are rather ineffective if non-existent.
Now time for two (fictional, but somewhat realistic) case studies:
Case study A:
Sharon is a 56 years old mother of two living in a lower-class neighbourhood. She's been married to Henry for 34 years. Their marriage is an unhappy one, however, since Henry is an alcoholic and has violent tendencies, meaning he tends to beat Sharon and they tend to argue a lot.
One day, after Henry arrives home late after a massive drinking session intoxicated, Sharon scolds Henry for coming home drunk again, for which Henry threatens to beat her. Sharon scolds her again for wasting all the money on alcohol, to which Henry replies:
"What are you going to do about it, kill me?" haughtily.
"I will!" cries back Sharon and grabs a knife.
"Do it, bitch!" shouts Henry, and a few moments later he was stabbed to death by Sharon.
Case study B:
Jerome is an adolescent boy from a poor family. His environment was very violent, many people he knew or grown up with was later victim to some form of violence.
One night he goes on to break into a house where only an old lady resides. As he was in her bedroom looking for her jewellery, he made too much noise which woke up the old lady. When the puzzled lady was to confront him, he killed her so he could get away.
Both committed murder. Both would be sentenced to death. And by your logic, it would be right if both were executed.
But if you paid attention to Case study A, it was only matter of sheer dumb luck that Henry became the victim and not Sharon.
What I wanted to reflect upon is that you keep treating all sorts of murders the same.