[english.elpais.com]corruption-that-swallowed-up-us-investment-in-afghanistan.html
This is an interesting report in the English version a Spanish Newspaper, summing up why the US operation in Afghanistan failed.
The black hole of corruption that swallowed up US investment in Afghanistan
Programs based on unrealistic objectives, excessive levels of aid and a lack of local understanding have contributed to financial disaster as well as military failure in the country
And Afghanistan's farmers are still growing heroin poppies to sell in America.
The Taliban will likely put an end to that. Their opium eradication policy was one of the most successful drug interdiction programs in history, they only backtracked after the US invasion because they needed western cash to buy weapons etc.
The key point in the failure is the wrong-headed nation-building attempt in a country in which the social, economic, and political structure of ethnic tribes and tribal warlords hash loyalty of the people. With the tribes having the primary loyalty of the people, there is no real nation state.
Exactly, it failed because it was a fantasy goal to begin with. Foreign conquerors are never welcomed liberators, Washington's wet dreams notwithstanding.