I would contend that Western efforts to design a Western style Democratic system for another society are doomed: we cannot design their government, law or social structure; we can only prolong the agony of their own reordering of their society.
We had the power, have the power to smash any organized state, but we cannot build a new one for anyone. The power to kill is not the power to give life.
A country like Afghanistan requires either a Monarchial or Authoritarian (not specifically Totalitarian) government. Those type governments are not bound by an equalitarian view of law and custom. Equalitarianism is anathema when differences in culture are clear. And too the ethnicities overlap. Should the idea of Democracy take hold, and it may have, there will be a break up and ethnic cleansing to define new borders.