This post at Global Guerrillas (along with the quoted Wired article) goes to show 1. how rapidly insurgencies in Iraq and Afghanistan have developed cheap, lethal explosives 2. how easily they can be made and deployed, and 3. the absolutely mind-boggling disparity between insurgent expenses and the multi-trillion dollar US military-industrial complex.
The main point I want to draw out is this: we've got two different economic incentives at work on either side:
A. ideological Islamic insurgent groups have low/inconsistent material resources, so they need the best bang for buck (literally) to fight the US. Thus, scarcity breeds brutal efficiency.
(yes, I am not factoring in unnamed foreign funders from Saudi Arabia/Iran/Pakistan or the heroin trade, but neither the Iraqi insurgent groups nor the Taliban have sophisticated, high-cost supply chains of any sort.)
B. well-connected military contractors and lobbyists in the United States making sweetheart deals to siphon as much of the vast US defense budget as possible, and a large, professionally-trained military using expensive manufactured equipment halfway across the world from their country of origin in a highly technologized, bureaucratized environment without consistently clear goals and endpoints. Thus, surplus breeds massive waste.
If I were a ranking Pentagon official, I would take a serious look at the war spending and try to figure out the millions of ways that millions of dollars could be better spent. But that might make too much sense.