However, do you seriously not agree that all things being equal, driving more slowly down a given stretch of road will reduce the risk of an accident? You original question suggests that you don't.
All other things aren't equal, so it's a moot point. By that logic we should go back to little men with red flags. It might be a simple example, but the fact of the matter is that it's not that simple. Driving slower will in all likelihood reduce the severity of an accident, but if you're away with the fairies then it won't reduce the probability of one.