I suspect that the support of the death penalty is rooted in the extremely natural, rational, and reasonable human desire for vengeance for evildoers. And our Constitution of course implicitly accepts the legality of executing such villains. Nothing wrong with that!
Now that is what the government is for. Not protecting the rights of voters, not balancing the playing field, not improving the economy for more than a few thousand people. It's killing its citizens. And for emotional reasons no less! How very liberal of you, using emotion as a driving force in political and legally murderous momentary satisfaction. Cost effective and rational, excellent.
PS - google rational, I don't think you're getting it