What is being claimed as people grabbing codes isn't quite correct. In the early days of keyless door locks, a single code was generated for each car and with the right receiver these codes could be picked up and used by someone else. But now, all the keyless door locks, and even garage door openers use rolling codes. So whatever code is used to open or lock a door, be it a car door or garage door, is changed the next time the signal is sent out.