No army can occupy the entire country
I've said before that a far better plan would have been to set up a network of safe settlements around the country (not necessarily in or near the existing towns or cities), each surrounded by a eff-off security perimeter and free fire zone, each provided with a airstrip, medical centre, housing, clean water supply, reliable electricy supply, schools etc etc. Any Afghans seeking our protection and accepting our moral values would be let in (minus their weapons), everyone else could carry on unmolested (at least by us) living their lives outside. Think of a series of Bastions dotted around the country, protected at least initially by ISAF, for pro-western Afghans who wanted to start living in a modern, safe environment.
I reckon in relatively short period of time many who elected to live on the outside (especially the younger generation) would begin to gravitate towards these centres, with all that they had to offer.