Re: I think it's a reasonable idea.
As long as there's oversight and "rules" for usage, I see no problem until someone gets the great idea to start "tracking everything". But yes, who keeps the package barcode strip with the MAC or writes it down and puts it somewhere.
The only real problem is, is it directional? So there's 40 people on a street, the device pings and says "I got one". Well.. which person has it? Is it one of the 40? One of those in a building or house?