Dr. Emily Weiss has confirmed through scientific research that simple pet id tags with name address and phone number can drastically increase the return to owner rate (RTO).
"The use of a simple ID tag that includes the name, phone number and address of the guardian would support community return of a lost pet. Ideally, lost pets with ID tags should never enter the sheltering system, as they are returned directly by the finder who calls the guardian’s number clearly displayed on the tag. This means we could decrease intake by increasing the use of simple ID tags."
Her research also indicates one problem: human laziness and/or ignorance! They gave ID tags to a number of new pet owners. Of those people that got free tags almost 75% reported that their pet wears the pet ID tag all the time. The same people, before their free tag, reported their pets only 33% reported their pet was protected all the time.
Here is a link to the article: Tagging Matters... and we've got the data to prove it