Between autism and Alzheimer's, tracking modules would really help local authorities. I'm sure if the government is involved it will cost a lot more. Garmin makes a really nice device for dogs. If you get the government involved it will only cost 5 times as much. Two words for you Obama Phone.
In most cases the family could share the location data with any agencies helping out. In the event of a serious problem law enforcement organizations have direct access to phone location data, as they would to the GPS tracking devices.