I agree that owners should be responsible, however nobody is perfect and accidents can happen, as even perfect owners such as yourself can be prone to the unpredictability of animals. Especially for new owners, who even armed with basic common sense, might not be able to figure out that Fido is burrowing an escape tunnel under the fence, etc. I think it's an absolutely sound option to be able to find your loved pet in the event that it does get into mischief! Which is better? Finding your mischievous animal before he freezes to death scared or finding him, bringing him back home, learning from the mistake, and saving its life? It's just another way to bring piece of mind to the owner, keep dogs from becoming strays, and reducing road kill. Nobody is saying this is a magic bullet in pet ownership and care!!!
Course ya do!
Probably the same reason that half of the stuff that you see on the web works. Because they "can".
I have a very small mind and must live with it. -- E. Dijkstra