The taliban are basically the tribal councils over the regions. You can think of it like mafia - but it is simultaneously less criminal and more brutal because they are adherent to sharia law, generally.
They are the cartel, they are many of the village/tribal heads, they are disgruntled youths, they are government officials. They are people who decide to pitch in to overthrow someone they don't like one day, and an average person the next.
These groups have always been amorphous and difficult to define with many of our own attempts to categorize them being projection moreso than reality. It would be like trying to say that everyone who ends up at an antifa riot is a card carrying member attending meetings and fully dedicated to the cause…. When half the people there lobbing explosives at a building might just be disgruntled former employees who have an opportunity to participate in violence targeting someone they have beef with.
Fact is, there was a lot of corruption there and some of it was our fault… Some of it is just how the region has been for so long. How do you have a modern representative republic when most of the population does not have a concept of individual rights or liberties? Many of the paradigms upon which our civilization is built are foreign, abatract, things to them and while they may be able to learn them or even agree with them - when you have an old blood feud with the tribe over the mountain and it's their votes that throw the polls the way you don't want… Why should you listen to them when you can shoot them like you've always done? The trust in the process to not be abused isn't there and so even when they understand and agree with the process, they end up racing each other to be the one to wield the club of authority and secure it for themselves. Which defeats the purpose of due process, representative republics, constraints of government, etc.