I think we can have it both ways. For a given rider, on a given trip, any fall will be safer if they are wearing a helmet. However, statistically, it is argued,

I think we can have it both ways. For a given rider, on a given trip, any fall will be safer if they are wearing a helmet. However, statistically, it is argued, many falls won't be much safer. And in fact, if they feel compelled to wear a helmet, the person won't ride at all. And many of the rides the don't take would be ones where the likeliest falls are likely to not be helped much by a helmet. I subscribe to the above reasoning. A population may be healthier if not compelled to wear helmets when cycling. But for me, I never ride without one. Ever. Short trips, long trips, commutes to work. I have mine with me now.