> That eliminates margin for corruption and lenience.

Lenience and mercy are critical components of a system of a just criminal justice system. We have judges issue sentences in large part because we want a human being with good judgement to decide how serious the punishment for an offence should be based on the circumstances.

A person who shoots their partner who has been abusing them for years should probably receive a different punishment than a person who pulls out a gun in traffic and shoots someone for cutting them off. Mercy or "lenience" are not inherently flaws in the justice system, though of course there's always "too much of a good thing."