The advanced militaries of the world (British Army, USMC, IDF etc) are set up for maneuver warfare. This is what is known as third generation warfare (see William S Lind), and it has its roots in the Blitzkreig practiced by the Germans in WW2. When a third-generation military meets a second-generation military (one that thinks in terms of position-holding and massed formations) in a stand-up fight the result is always a rout (e.g. Six Day War, Gulf War 1, even Rommel virtually conquering France with a single armoured division). The Soviets knew this. Their genius strategy in WW2 was to force the Germans to fight in a second-generation style (and the Germans fell for it). This is also a major reason the Soviets were reluctant to enter Western Europe. All Western militaries thought very hard during the Cold War about how to defeat the Red Army, but the Prussians knew it all along.
Unfortunately the Taliban are a fourth-generation military (adept in psyops and propaganda, insurgency, guerilla tactics, information warfare) and the West is not well configured for that (and can't become so easily, as there are still second-generation potentials enemies around - we have to think in third-generation terms still).