Just curious, how old is the ticket processing database? Is it possible that 7 X's was an invalid licesnse plate at some point in the past? If so is it bad design still? What is the bad design in that case, the system or the improper requirements gathering when updating some parts of the system to allow for the 7x license plate? Is the actual problem not in the software, but in a failure to notify and properly train the police officers one the 7x problem?
It sounds more like state policy on valid license plates changed, and the software that handles this -- somewhere -- hasn't been updated to reflect this. This sort of things happens at work too, depending on how hacked together your software is for each department.