Yes, literal feuds. Cycles of tit-for-tat revenge that involve violence or are likely to escalate to violence unless the injured party (or their surviving relatives) perceive that “justice has been done” through state-imposed punishment. I lived in West Virginia, which such feuds were common before effective law enforcement was substituted for private revenge.
This is clearly not an argument for punishment in the case of victimless “crimes” or offenses unlikely to provoke escalating retaliation.
We do use mercenaries: http://www.newsweek.com/2010/08/10/mercenaries-in-iraq-to-take-over-soldiers-jobs.html
But there might be cheaper options. If we paid Afghan girls $10/day to go to school, would the Taliban collapse?
We could be a little more subtle. Start by offering jobs to do something the Taliban wouldn’t consider threatening—Mechanical Turk work-from-home stuff not requiring literacy, via some kind of specialized radio or satellite link with no access to porn or feminism or anything the Taliban would object to. Every family wants one of those terminals and they can make twice as much money if the girls work (from home) too. Gradually offer higher pay for higher skill levels, starting with nonthreatening stuff like arithmetic but escalating to translating the Koran and then to tasks that would involve reading a wide variety of secular material, analyzing political and judicial systems of different countries (still maybe disguised as a translating job)…