Just asking around re who has seen any good discussion/sources on why the Taliban seems headed to an easy victory following 20 years of US occupation and war against them.

One easy way to approach this for leftists is to say, well, even though the Taliban are horrible, they became in effect the Afghan national resistance to US occupation. Trouble is, while it sounds neat, it does not seem to correspond to the reality (perhaps to some extent, but not for the most part). Evidence suggests the Taliban have very little support among the population, and very significant parts of the population are terrified of their advance, notwithstanding the corruption and venality of the US-backed regime there.

In other words, why hasn't the US, simply from the point of view of its own interests, been unable to form, train and equip an Afghan force capable of defending itself from the Taliban with the US gone?

Is it simply that the Afghan regime has no legitimacy in the eyes of much of the population, due precisely to its reliance on US occupation? Or that due to its very nature, the regime that includes former warlords etc is unable to organise an effective resistance no matter what? Perhaps all this is true, but I'm not so much interested in leftist formulas, but in detailed analysis.