Force equals mass x acceleration. This explains why, all other things being equal, it behooves you to use a heavier bat when hitting a baseball or to weight 350 pounds if you're a nose tackle.
It also means that if you get hit by a Chevy Suburban at 30 mph you'll be in much worse shape than if you were hit by a mini Cooper. Yet someone caught speeding in either of those vehicles receives exactly the same fine. Now, one aspect of setting a speed limit has to do with sight lines, reaction times, etc. But not always -- there are plenty of streets where the speed limit could be much higher, but since it is a residential neighborhood with children, a commercial area with a lot of pedestrians, etc., the speed limit is much lower, meaning that one aspect of the speed limit is the recognition of limiting damage when the inevitable does occur. So maybe instead of speed limits we should have force limits.
No, I don't think this is actually do-able, but just as a thought experiment. And actually, now that we're on the topic, if the point of traffic tickets is to discourage behavior, shouldn't the ticket amount be normalized to income?