I may as well point out the Soviets had bounties on the heads of various field commanders during their 10 years in the country, and none of the major ones ever got captured.
I think you need to consider that the Taliban are not exactly the popular guys on the block in Afghanistan. While many non-afghans and some nationals support the Taliban, I believe most Afghans really do look forward to a Taliban free Afghan.
I agree that tribal forces will unite to fight a common foe, but at this moment most of the tribal forces do not view America as the enemy, but rather a liberator.
That of course could change in a heartbeat for about a hundred reasons.