I volunteer at my local shelter and I am currently training to do behavior evaluations to help relieve some the burden the current budget cuts have out on the staff. Even overworked and underpaid, the staff there IME working with them scan the body and scan with both scanners they have. Does this mean every shelter is this way, no, but I think alot of people paint shelter workers as being kind of lazy about microchips and that is not what I have observed. Most really want the animals to be reclaimed and reunited.