[throwaway373438]

Why would you care about per-journey statistics? Surely all that's demonstrating is that cars are often used for very brief, non-highway travel.

When the question is of how to travel between cities or states, why do you find the relative safety of low speed non-highway driving to be relevant?

[kqr]

Maybe because the choice I make as a consumer isn't between going to Hawaii by flight or by car -- it's whether to make a plane journey to Hawaii or a car journey upstate.

So maybe per total hour from door to door is the relevant metric: you tend to make decisions based on comparable travel times, whatever the reason for travel or mode eventually selected.