Whether there's justice or not in a rapist serving their sentence and going free (given that, one assumes, the sentencing guidelines were decided by dispassionate thinkers trying to reason about society as a whole)... It goes out the window if a family lives in so much fear they decide to "fix" the issue by taking the law into their own hands.

Then the society has to decide whether to jail the family, and so on.

Hammurabi's code seems harsh by modern standards, but at the time it was positively progressive. It was attempting to replace a retaliatory tradition so bloody it could wipe out entire bloodlines. He was trying to impose an upper limit on consequence to allow a society of semi-strangers to reach some meta-stability.