My assumption has been that worrying about the unfashionable nature of bike helmets was mainly restricted to the developed world, and that people in the develop

My assumption has been that worrying about the unfashionable nature of bike helmets was mainly restricted to the developed world, and that people in the developing world were likely not wearing helmets because they are an added expense (above and beyond the expense of just getting a bicycle in the first place). It is possible that airbag devices could 'save many lives' (if helmetless riders wore them), but I am not convinced that more wouldn't be saved by wearing helmets. That said, the work on putting airbags on the exterior of vehicles to protect cyclists and pedestrians seems very promising, and I hope it comes to market soon.