Muddy Point

From the reading the muddiest point i had was regarding RFID.  It is stated that it is tracking device that is used for a safeguard.  Yet a lot of people question their use for a privacy issue.  If the RFID can be used to deter theft, help users check out their own materials and help librarians re shelve materials and help to use staff in a more economical way--why is it so controversial?