JuJu Bean. We cannot have a CHEAP death penalty, no matter how much you would like it. We are guaranteed Life, Liberty, and the Pursuit of Happiness. It might surprise you that it is actually quite difficult to take someone's life without due process, and that due process involves lengthy and involved legal proceedings. 

Civilized nations do not execute people, and it will absolutely blow your mind to learn that states without the death penalty have lower murder rates. Whaaaat? I know it hurts. 

http://www.deathpenaltyinfo.org/deterrence-states-without-death-penalty-have-had-consistently-lower-murder-rates