Confidentiality assured?
Perhaps confidentiality was assured, but its equally as embarassing to destroy data as it is to simply loose it. In this case at least it was only a limited amount of data- but a lot of it concerns fines paid for motoring offences and time sensitive documents that were to be lodged with the courts. So- potentially there are people out there who may end up with penalty points or summons over matters they legitimately considered closed. It may not be as bad as loosing millions of bank account details- but its inexcusable nonetheless.
Shane