Then just note the vehicle volume and don't divide your deaths by volume? When you divide your deaths by volume you're implying that there's some value in a metric that amortizes deaths by vehicle volumes. Automobile volume is just one of several variables and simplifying this equation is why the US has a much higher traffic crash and fatality rate than any other developed country in the world.
What is the point of "noting" and not dividing? Sure, you can normalize by all sorts of different metrics. That doesn't mean you shouldn't normalize at all.
