Taliban does not want to hurt USA on US soil, only hurt USA on their soil... Al Qaeda wants to hurt USA everywhere. I think that is the big difference.
It is not our business or capability to stop Taliban. We can't be there forever. Once we leave, Taliban comes back. People who worked with the west (forced or volunteer) will probably get killed. Afghan army/police certainly wont be able to hold Taliban back by themselves.
thats the problem with "one size fits all" forced democracy.
Americans have no idea of the Afghan culture, their ethnic and tribal loyalities - nor do they give a fuck.
Yes, our troops have done some good things, but the bad outweighs the good sadly. The Afghan military can barely defend themselves.
We are stuck there forever.