I disagree; I don't want to spend 10 hours traveling, I want to get from point A to point B. Unit of distance is what makes sense. Who cares if I have half the chance of dying per hour, if I have to spend ten times the hours subject to that risk?

I'm not sure why you think just doubling the speed would impact the crash/unit of distance ratio. If ten planes do a 600km trip and one crashes, that's 1 crash per 6000km regardless of the speed at which they're traveling.

You're right that fixed per-trip risks are diluted, but that's because plane trips are longer, not because they're faster. The right comparison, in my opinion, would be to draw the curves of death rate / trip length.