The duration between when the pedestrian collapses and when the driver runs over the pedestrian is not as relevant as you seem to be implying. If someone is standing in a crosswalk in broad daylight and falls over, even if the pedestrian collapses 0.1 seconds before someone runs them over that doesn't leave the driver blameless. Why, in broad daylight, in the middle of a crosswalk, was a driver 0.1 seconds away from running over a pedestrian? That sounds like poor road design, poor driving, or another factor. The same logic applies even as we worsen the conditions: if it was dark, where was the lighting? If the pedestrian "suddenly appeared" from behind an obstacle, why is there an obstacle that close to a road and why can a pedestrian get so close that they can "appear" from behind that obstacle?

Roads should be designed so that pedestrians cannot accidentally end up 0.1 seconds (or pick your duration) from being crushed by a driver. And drivers, state-licensed machine operators, should face an incredibly high bar of scrutiny when it comes to damaging pedestrians. Yes this probably means very different road designs than the ones we have now, that is one of the end goals of this kind of effort.

This is the key point of the research and the tool I built, and clearly I still have some work to do on making this clear on my site:

The objective is not to shift blame from one party to the other, even if its shifting from VRUs to drivers. The important thing is that we emphasize that all car crashes have a cause and known solutions! Nearly all news articles miss this point, and tend to place blame (even inadvertently) on the parties involved rather than discuss how to prevent future incidents from happening.

If the collapse is shielded from view until the last instant, but still possible, there's an engineer somewhere who designed a road irresponsibly.

It is extremely unlikely that someone will be killed by a 5 mph collision, and it is certainly less likely than a 30 mph collision.

> you are presumably a novice after all

I'm 49 and I've been driving since I was 16.

You can absolutely react to hazards without appearing skittish, which also alerts other traffic to the hazard if they're paying close attention.

Trying to drive like a robot all the time is something that actual novice drivers think makes them better drivers.