I know in Greece, their stray dog management system is to take the dogs to a shelter, where they are spayed/neutered, given all appropriate vaccines and health care, then given a certain amount of time to be adopted. If nobody adopts them, they're released back to the streets. I assume there's some way to identify them so they aren't taken back to the shelter. Maybe Turkey does the same thing, and the ear-tagged dogs are the ones that have been TNR'd. That would be my guess.