The problem of driving while sleep-deprived will likely be solved by robocars more than by any altruistic efforts.
I don’t know how much time this would take, but of course when we evaluate the scale of the problem, we should put into our calculations robocars eliminating traffic collisions at some point.
The rest of the problem seems better tackled by focusing more on the stresses that cause sleep problems, and by relatively decentralized efforts to shift our cultures to be more sleep-friendly.
I might be overestimating the amount of people that are sleep-deprived only because they don’t prioritize sleep (due to being unaware of its benefits and the costs of being sleep-deprived (both benefits and costs are very significant, according to the book and the research it references)). But if the number of these people is not trivial, getting them to sleep more seems to me like a strong combination of scale+neglectedness+solvability.