I disagree. I made 1 statement saying that requirements aren't explanations, 1 statement that I observed a rural carrier use a jeep for years, and then a state

I disagree. I made 1 statement saying that requirements aren't explanations, 1 statement that I observed a rural carrier use a jeep for years, and then a statement that jeeps are in fact commercially available. I would certainly expect a jeep with a mirror bolted on the traffic side to have better rear and side visibility than something with no glass in the back, so go ahead and hang your hat on visibility if you want.