For one it is dumb to assume you wont be raided and sent to pound me in the ass prison for a small personal use interception, people go to prison for personal use amounts of drugs on a regular basis and you are not special just because you get your drugs shipped to you. Second of all, it would be primarily for importers. RFID would be able to send the signal 100 feet away if it is battery powered, you should be able to covertly get a reading on it. Also could use chips that send signal via cellular network for even more distance.