While I'm on the topic of Giustozzi, here's something else which is important. One of the biggest motivators for a village to support a Taliban presence is a dispute that the official authorities, in so far as they exist, or the tribal authorities have failed to solve, or have solved in a manner that seems unjust. Another is a desire for security. But this is qualitatively less important; there is a huge difference between "security" and justice.
After all, any half-arsed authoritarian regime can at least claim to be providing security - patrolling, locking people up, shooting other people, maintaining a network of informers, battering suspects - all these can be described as "security". But it's almost characteristic of authoritarian and failed states that the state itself is a major insecurity producer.
Which brings me to my point. The reason why so many Islamist movements that succeed lay a lot of emphasis on the judiciary - the Islamic Courts in Somalia didn't bother to give themselves any other name until after they'd set up shop in the presidential palace - is also the reason for their success. Giustozzi argues that a lot of Afghans don't actually support the content of the Taliban's lawbook very much. What he doesn't go on to say, but perhaps should, is that this implies they choose law in general over lawlessness.
Given the choice of what is marketed as order without law, but which as always turns out to be chaos, and some sort of legal order, the people pick the latter. And they are far from being too stupid to recognise the difference between a government which practices legality, and one that merely has a lot of statutes containing agreeable features requested by foreigners, like Ishmaelia in Evelyn Waugh's Scoop. Let's be clear - practice beats constitution-writing. Legality is not something decreed in the capital.
Franz Neumann's Behemoth is one of the guidebooks to the last eight years. Neumann wrote in 1942 that the defining feature of the Nazi state was that it claimed to be Hobbes' Leviathan - the all-powerful creator of minimal order - but was in fact more like the Behemoth, the Leviathan's mythological partner, an equally mighty creator of chaos. He argued that this is true of authoritarianism everywhere; it's worth remembering that when he wrote this, he was thinking of the pre-war Nazi state founded on the idea of the Ausnahmezustand, the state of emergency in which (the legal) order is itself suspended.
Eventually, the difference between law and order is how the police behave, on a mountain road at night.