That sounds like a strawman argument. If you don't wear a helment while doing activity A, why wear it while doing activity B.
To answer your question, perhaps because the common factor in all of these activities is that I am moving relatively slowly and my surroundings are basically stationary. These factors are void if I am riding a bike (or a motorcycle), where I might be moving at a few mph and there could be vehicles around me that might be moving even faster.
To answer your question, perhaps because the common factor in all of these activities is that I am moving relatively slowly and my surroundings are basically stationary. These factors are void if I am riding a bike (or a motorcycle), where I might be moving at a few mph and there could be vehicles around me that might be moving even faster.