Its true, atleast in my experience!
I lived in Multan for 5~6 months ('95), during that time I had a couple of cars with Peshawar reg (PRN 790 & PRG 906). The police there gave me hard times for no reason. Stop us for no reason, follow us for no reason, ask stupid questions for no reason, etc, etc.
Once I was going to punch one of them if my uncle didn't stop me from doing so. He used to grease their palms, cough up some bux or scratch his pocket and shake his wallet to get us rid of those bas______rds!!!
May ALLAH help us become ONE NATION!