A person designs a machine gun but does not pull the actual trigger. There is an army officer that orders the weapon be deployed and the rules of engagement for when it can be used.

A person designs a killer robot but does not activate it. There is an army officer that orders the weapon be deployed and the rules of engagement for when it can be used.

There is always a person that is responsible for the use of a munition. Maybe that person is higher up the chain with a killer robot than a machine gun. If you want to launch a nuclear bomb then it goes all the way to the top of the chain. But there is always a person that is responsible for the death caused by the munition.