They should have sent NZ troops in instead of your trigger happy Marines and Para's and other supporting elements. NZ troops have the best experience with hearts and minds projects. We are, effectively, a peacekeeping force. Just look at our operations in East Timor, sure people are being killed, but it isn't as violent as Iraq or Afghanistan. The NZ troops have experience in the goals the US are trying, but aren't achieving.
Fact is, the general populace of Afghanistan hate the Taliban. They have mutilated them, destroyed their lives and exerted a vicious rule over them. However, they do promise things that will make the people want them instead of the current rule, like promises to stop bandits attacking food carts and so on that travel between towns. They also protect the Opium farmers. The farmers don't have a choice when it comes to farming opium, its the only way they stay alive because it's worth so much.
It's also about culture, our culture is so incredibly different to theirs, we can't try impose our regulations on them, our style of rule because they aren't used to it, they have totally different values. They don't see the irony in employing a teenage opium addict in an opium field. It's just so different.
We can destroy terrorism, to an extent. Many organizations fall apart once their leaders are gone. We can't get rid of the idea, but we can get rid of those with the will and resources to act upon it. Take the war on drugs in Colombia. The ISA found the intel, and handed it to the SEALs and other para-military forces, who slowly dis-assembled the cartels member by member. Sure, it's still there, but it was a very very effective way of dealing with it. All we need to do is remove those people in positions of power and influence, and the rest falls apart.