No idea how car sales taxes work for soldiers in a war zone in most of the country. It’s a state’s issue, not a federal’s issue. However, most of a soldier’s pay is tax exempt at both state and federal level while deployed in a war zone. (Generally speaking, states never collect taxes on soldier pay anyway, they are not stationed in their home state much of the time, thus, it is income generated in a foreign state and exempt from home state income taxes. Top that off with most bases located in states that do not charge income taxes on soldier pay, and you can see why most states get no soldier income taxes.)
But I agree, soldiers should be 100% proof against taxes. I’d even say they should be able to keep their sales receipts and get reimbursed all those taxes as well. It’s not like we are making privates into millionaires, heck, most soldiers earn less then those who live in cardboard boxes and panhandle all day! (It’s not even an exaggeration of the truth, but it’d be close to find out which one actually makes more money.)
Then again, I’m biased. I know what a private is paid, I’ve been there. You are not exactly running out and buying an 800 square foot residence, let alone a Ferrari! heh.