Either you don't belong to tribal area, or you have never read the history of tribal areas. please read the history, read why NCP are allowed? OR try to lodge a complaint at the office of political agent of your area, and he will explain why NCP cars are allowed and legal.:S.
Just typing on a public forums will not solve the problem of stolen vehicles, you have to go and talk to your area administrator, and struggle against stolen cars.
For your kind information NCP cars are fully legal in Tribal areas, FATA and PATA.