To understand why this is so common, you need to know about Pashtun culture and methods for dealing disagreements. Great article at the Economist last year - "Honour among them; Pushtunwali.(The Pushtuns' tribal code)" It's sadly behind a feewall, here's the link: http://www.economist.com/world/displaystory.cfm?story_id=8345531

If someone finds an open version, please post the url. I know you can get it through a reg-page via findarticles.