I think Ring devices should have a serial number on the device and each time someone tries to activate a new device they must give the serial number. Once they give the serial number the serial number should be scanned to see if that item was reported stolen. If it has been reported stolen the device should not be able to be activated.
I think they do that, but electroinically, no need for a physical etched number. If a device has been registered to someone else, you cannot activate it unless the original owner has released it.