Originally Posted by The Seldom Kill
Such tags could be treated in the same manner as license plate
The range of an RFID chip is extremely small. They are also have no internal power source, which makes them unable to transmit on their own. In order to activate and "read" and RFID chip, a scanner is used. The scanner can only activate the chip from a limited distance.
These are the same chips that have been used for years in pets. If a pet gets loose and animal control picks up the pet, they first scan the pet to see if they can identify the owener.
An RFID chip fulfills the same role as a bar code, except it can contain more information than a bar code can. In order for a cop to read an RFID tag in a bike, they would still have to stop the biker and scan the bike for the RFID tag.
For more information on how these work, see here:
http://electronics.howstuffworks.com/smart-label.htm