None of the three people I've seen get hit by cars in the last week or so were wearing helmets. Nor were more than 10% of the dozens, perhaps hundreds, of cyclist witnesses to said collisions. None of the "victims" of said "accidents" suffered head injuries, but two did sustain broken bones. Perhaps the cyclists of Copenhagen, given the 1.2 million kilometres they cycle every working day, know more about real world risk assessment and injury prevention, and about the utter pointlessness of wearing polystyrene lids, than many UK pro-helmet cyclists, maybe?