The reason cars aren't flying off the road on dark two lane winding rural roads whenever another car comes their way is not because they can see much of what's around, it's because they don't panic - they have enough information to keep going - a handful of reflections, the path that the headlights followed, memory, etc.. They don't have to worry about little ruts, potholes, debris, little animals, etc., and when they do veer into the gravel or even a soft shoulder, it's no big deal.