At least in Finland hunters use this sort of things for their dogs.
Would be neat for all the dogs, though.
I work as a volunteer for an association that helps people when they've lost their pet. We have a hotline where they can call and we give advice and if needed we go there with a trained tracking dog. Me and Manu are still in training to be tracking dog, but maybe someday we will be able to help people find their pets. I work on the hotline, though.
If every dog had this thing we'd have to find a new hobby.