If people can be nudged by street design or transparent B-pillars, they can also be nudged by heavy penalties that are commensurate with the deed.

This would only work if the penalties were enforced a very large percentage of the time someone did something unsafe, regardless of the outcome. Humans respond to light punishments consistently applied far better than harsh punishments rarely applied.

It would be far more effective if you applied a $5 fine every time a person looked at their phone screen while driving than if you instituted the death penalty which applied only when a distracted driver kills a pedestrian.

Which is why there are no murders in states with a death penalty.

It seems like you're effectively saying MADD didn't work. Drunk driving never became less than it was in the late 1970s

https://en.wikipedia.org/wiki/Mothers_Against_Drunk_Driving

The claim they lowered drunk driving deaths by 1/2. I have no easy way to verify that but if true it certainly suggests people's behavior can be changed

I don't know about your area, but where I live the police set up checkpoints along common routes home from popular bars/restaurants to catch drunk drivers. Drunk drivers get caught extremely often and many of them lose their licence for long periods of time.

This does not discourage drunk driving as much as you would think. It does remove a lot of the drunk drivers from the road by force, however.

MADD only worked in the sense that it made some mothers feel somewhat absolved of whatever guilt they felt for losing a child. Their statistical claims are quite ridiculous, though.

Edit: Claiming credit moreso than flawed statistics, although both are highly questionable.

Enforcement works in societies which actually enforce their laws. Try finding weed in Singapore for example.

Do NOT try to get weed there.

You probably could, however, find hordes of repressed maniacs and neurotics discouraged enough by it to hesitate a bit. At least if you could keep them out of motor vehicles ;)