It's not about the punishment fitting the crime, it's about it fitting the morals of the punish-er. Being tally-ho for public execution shows you are no better than them. The reason they hanged outlaws in the wild west is because it was cheaper than lining them up and shooting them, and the citizens of ye olde' days didn't really take kindly to some ruffian stealing **** they absolutely needed to survive. Nowadays we have more effective means of execution, and still we reserve them for capital offenses.