The reversing light on your 1993 Ford Fiesta coming when you put the car into reverse why is this?

Backup lights, also called reversing lights, "R" lamps, or white backup lamps, are a component of the lighting system of motor vehicles. They are used to assist the driver when reversing the vehicle. They enable the driver to see objects and people behind the car, preventing accidents and potential injury while in motion.

The reason the backup lights come on when you put your Fiesta into reverse is because they are designed to do so. When the gear shift is put into reverse, a signal is sent to the backup light switch, which then turns on the backup lights. This is a safety feature that helps you see when you are backing up and helps to prevent accidents.