Being "Grandfathered In" used not to be uncommon in many situations. When a new qualification requirement comes in its often not feasible to require that everyone who is currently doing the job should immediately take the new test, do the new training or whatever. Enabling existing staff to be grandfathered in to the new system keeps the system going while new staff are trained and examined. The period when people can apply to be grandfathered is usually brief and the qualification tight....usually something like x years service and a clean record. As the workforce ages those people naturally leave the service. When the driving test came in, people who were already driving could apply for a licence without being tested. Similarly my father never took a driving test. He learned to drive in the army and on his demob, he applied for a civvy driving licence on the basis of his army experience.