This is a common misconception. It’s significantly more expensive to sentence someone to death than to sentence them to life in prison due to the extensive appeals process involved in a capital sentence. There is also the issue of wrongful convictions. Not every situation is as cut and dry as this and there is no perfect means of preventing innocent people from being executed in a justice system with capital punishment. Just because something feels good at a visceral level doesn’t mean it makes sense in practice or is true justice.