The example of Diyah1 concerns accidental killing or breaking a person's hand or foot in the stated legal discussion.
Human life and bodily parts are not physically or meaningfully equivalent to wealth. The monetary substitute is therefore not something one invents by saying that the two are alike. Shariah appoints it so that the loss does not go without redress.
This illustrates Mithl Ghayr Ma'qul: the substitute depends on legal appointment, not on an independently obvious likeness. It is a classification example, not permission for personal enforcement.
1. Diyah: the monetary compensation referred to in this legal example of loss of life or bodily injury.
- When Money Is an Appointed Substitute