This assumption was valid twenty years ago when most of us had only one or two PIN codes.  However, in today's e-world where we are required to recall a multitude of PIN codes, passwords, passcodes and lock combinations, that same assumption is totally unrealistic.  The security of the PIN system is focused entirely on preventing unauthorized access while ignoring our inability to recall sets of meaningless numbers.  In response, WE CARRY COPIES OF OUR CODES AND COMPROMISE THE INTENDED SECURITY!