Hugh,
In regards to this letter, I suspect that the ID is not so much an overt surveillance mechanism but rather a tool to prevent and or apprehend those who traffic in stolen merchandise. Locally, pawn shops are required to submit daily reports to the police department cataloging all incoming merchandise, and there is a “pawn shop detail” of officers whose function it is to review and compare those records to reports of stolen goods. Several well-documented arrests of burglars and others dealing in ill-gotten gains have resulted. – C.S.