A few years back the Americans were convinced (the Pentagon going so far as to issue a security alert) that we Canadians were spying on American contractors with radio transmitters in coins. Turns out the Americans were afraid of the painted poppies on a special release of quarters honouring the war dead. These secret compartment coins may be neat for smuggling, but honestly they wouldn't be any good for tracking people. Everyone knows all the Canadian quarters end up at Tim Horton's almost as quickly as you get them so the best that would happen would be that we could track how quickly the contractors fall under the sway of the donuts and coffee. :)