GPS

The only similar example of this I can think of is when young children from elementary schools go on a group field trip and have their names attached to them in case they get lost.

Given how modern technology has advanced virtually everything about the Olympics, including how races are timed, cameras are now all state of the art HD, and equipment and clothing are better than ever before, I would like to know why runners names and numbers are still identified using pieces of white paper attached to their uniforms using SAFETY PINS. This is literally like using diapers from the 1950's. It would be so easy to use any number of high tech methods to do this, yet this prehistoric practice continues.