War of attrition encompasses guerrilla warfare which is what the Taliban used, see definition: https://en.wikipedia.org/wiki/Attrition_warfare

War of attrition does not mean casualty numbers, it means the goal of the war is to wear down the enemy so that their will to fight collapses which both the Taliban and the US tried to do, see: https://www.csis.org/analysis/afghan-war-attrition-peace-tal...