I mostly agree, but that's true any time you wrap a complex problem up into a single number. I am merely arguing that, if we pick a single number, deaths-per-pa

I mostly agree, but that's true any time you wrap a complex problem up into a single number. I am merely arguing that, if we pick a single number, deaths-per-passenger-mile is much better than deaths-per-licensed-driver. I guess you are saying that deaths-per-trip is an even better number. That would be interesting to see, I agree, but as an additional number, not a replacement.