As much as the Taliban like to use roadside bombs and anti-vehicle mines in Afghanistan, they still find themselves fighting foreign troops on foot a lot. That's because, especially in the mountainous areas of eastern and northern Afghanistan, it's difficult to get MRAPs (armored trucks) or armored hummers up into those hills. The MRAPs are particularly difficult to move cross-country, because their V shaped undercarriage design (to deflect blast) gives the vehicles a higher center of gravity, making them more prone to rolling over.
Despite the greater safety of MRAPs, many troops still prefer armored hummers, especially if most of the travel is cross country. This avoids roadside bombs and mines, and gets you there (in most cases) faster than going on foot, and more safely than via MRAP.
American and NATO infantry often have to check out remote villages on foot. Here they are at a disadvantage, because the foreign troops carry three times the weight of gear and weapons than their Taliban opponents. While the foreign troops have lots of air power, all the troops can always depend on getting are UAVs, often the five pound, unarmed, Ravens. If a large group of Taliban are encountered, the enemy can often escape cross country, especially if you cannot call in a manned warplane or helicopter gunship quickly. Worse, the Taliban can take shelter among civilians. The new ROEs (Rules Of Engagement) prevent the use of air power when civilians are about.
While the Taliban eventually lose those battles in the hills (especially if there are warplanes available, and no civilians for the Taliban to use as human shields), they believe that their ultimate weapon is time. The foreigners will get tired of chasing the Afghan gunmen around, and go home.