You're addressing here something different to the civil sentence of capital punishment and it's purpose. We are all certainly going to die but civil authorities are not granted omniscience by Scripture and have to judge within the realm of 'the common good' for which they are responsible.
Put limits for the people around the mountain and tell them, ‘Be careful that you do not approach the mountain or touch the foot of it. Whoever touches the mountain is to be put to death.
“Anyone who strikes a person with a fatal blow is to be put to death.
But if anyone schemes and kills someone deliberately, that person is to be taken from my altar and put to death.
Anyone who kidnaps someone is to be put to death, whether the victim has been sold or is still in the kidnapper’s possession.
If, however, the bull has had the habit of goring and the owner has been warned but has not kept it penned up and it kills a man or woman, the bull is to be stoned and its owner also is to be put to death.
“Anyone who has sexual relations with an animal is to be put to death.
“Say to the Israelites: ‘Any Israelite or any foreigner residing in Israel who sacrifices any of his children to Molek is to be put to death. The members of the community are to stone him.
“‘If a man commits adultery with another man’s wife—with the wife of his neighbor—both the adulterer and the adulteress are to be put to death.
“‘A man or woman who is a medium or spiritist among you must be put to death. You are to stone them; their blood will be on their own heads.’”
There are many more that call for capitol punishment