imagine doing 30mph on a straight road with high visibility and spotting activity on the side of the road ... you automatically become more aware of that space and watch it closely. I know I do, since I failed my driver's test because of such a situation and I should have seen it coming (doing 65mph, no less)
and hitting a dear at 100kmh at night is not the same, no one could save that situation, except maybe a self-driivng car