Americans have never been much for learning the lessons of history.
Part of it is that America is so different from other nations, founded on principle rather than ethnicity or geography.
A corollary to this is the myth of American exceptionalism, which, loosely translated, means: "Others failed in the past because they did it wrong. When we do things our way, we succeed. Plus, we've got God on our side."
When it comes to Afghanistan, a backwater that has been notoriously hostile to outsiders, "The Graveyard of Empires," we may learn that even our way won't win us the highway.
Take the Brits, for example. If you have any FAQ's about how to run an empire, they're the go-to folks. Anybody who can subjugate the entire Indian subcontinent--several hundred million people--for over a hundred years using nothing more than a few thousand civil servants and soldiers must know what they're doing.
Well, Afghanistan's inhospitable inhabitants and topography broke them, too. Even the Russian Bear lumbered off with a bruised backside.
Do we honestly think that we can cram our Age of Enlightenment ideals down the locals' throats and leave them with a functioning agrarian democracy in the Jeffersonian mold (well, growing opium poppies is a form of agriculture) through military might, just because we happen to be more charming than our predecessors?
It doesn't matter who's sitting in the Oval Office hot seat, be they Democrat or Republican. When it comes to Afghanistan, they're earning every penny of their salary.