> will enforcement of the rule bring back those 100 people?

Yes. Enforcement of the rules, when done properly, does save lives. We have psychology studies that show that judgement/punishment needs to be swift/certain. When that is the case, human behavior is altered (sometimes permanently).

> and that in real life you won't get 100% compliance and enforcement

No one needs 100% compliance. We need something up near 98% or 99%, which is achievable.

Sure, the results have to be measured and the rules adjusted. But a possible result of this rule is exactly that it will make drivers drive more slowly in general, for fear of hitting pedestrians, which would overall reduce accidents, even outside of pedestrian deaths.