This brings up a very important point that I try to keep raising. The Americans were not averse to something like a war tax being imposed. We would have gone for it. The political elites were afraid to ask us to do it.
You should go back and look at the debates at the time. In the case of Iraq, the argument was that a tax was unnecessary because the war would be short, of modest cost, and that most of that cost would be paid for by Iraqi oil revenues after the war. It's a similar story with Afghanistan, except the cost was modest (15-20 billion a year for the first five years) so a tax wasn't deemed necessary. Tax increases were not considered after that because we were always just a Friedman Unit or two away from winning or leaving....