It all comes down to a question of ethics and humanitarianism
You could theoretically acomplish the same by life sentences.
at a greater cost.
But then again a human life is supposed to be priceless.
I hold to the belief that human life is of value.
And that if someone offs 2 people and you off him, youa re no better, and the total victim count is now 3.
The end resut of ife imprisonment is, ironicay, death. So isn't ife in jai effectivey ife unti you die the same way you woud be before given the death penaty?