The wearing of a helmet whilst cycling in the UK isn't mandatory.
Advocates for helmet use say using one will protect the wearer in the event of an accident, reducing the severity of the head impact.
Opponents claim if a car travelling 30 mph collides with a cyclist, a helmet will make little difference to the outcome.
Neutral view, not every accident involves cars at 30 mph. It could be hitting a pothole, swerving to avoid a pedestrian stepping off the curb, a loose dog on a shared path, gravel on a bend in the road, Dooring (a car door being opened ), wet leaves or icy puddles. In these situations a helmet could mean the difference between a fractured skull and concussion.
Advocates; a helmet makes the rider feel more safe in traffic or at speed.
Opponents; wearing one makes the user take risks they wouldn't take without one.
Neutral; idiots will take risks without helmet use, is it not better they have one on when taking risks?
Advocates; if car drivers have seatbelts, airbags, bumpers and a roll cage, motorcyclists wear full face helmets, gloves and leathers, why shouldn't cyclists have a barrier between skin and the ground.
Opponents; cyclists travel at lower speeds than other road users, why would they need protection?
Neutral; tripping over a loose slab when walking on the pavement can mean a sprained wrist, twisted ankle or cuts and abrasions. With a rise in the use of ebikes, more people are travelling at speeds they previously wouldn't go. Road bikes without motors can easily exceed 30 mph. Tarmac hurts at any speed.
Advocates; shopping for helmets is easy. They are available not only from sports outlets but from supermarkets and catalogue retailers ( Argos ).
Opponents; helmets are expensive, hot and make you sweat. Nobody wants to arrive at work sweaty.
Neutral; helmets have evolved greatly from the days of the leather hairnet style used by the '70's racing cyclist. With more protection, lighter weight, better venting and a more secure fit, helmets are safer and more comfortable. They all pass the same UK safety rules from the cheap at Asda to the expensive from Wiggle. With a wide array of colours, visibility is also improved. If you arrive at work hot and sweaty you may be overdressed and cycling too hard. Consider an ebike or an easier route to work.
There are pro cyclists who claim that helmet use shouldn't be compulsory ( even though the team they ride for makes them wear one). The Netherlands, known for extensive bike use, has the lowest rates for helmet use but also the lowest fatality rates.
There are also plenty of stories from commuters and everyday cyclists of how wearing a helmet prevented serious injury. The T's & C's of sportive, audax and charity rides state helmet use is compulsory.
Possibly, instead of berating the victim, educating the perpetrator would lead to a better outcome. Akin to telling a victim of gun crime they should of worn a bullet proof vest , instead of policing gun sales. Or maybe the answer isn't helmet use but a better road infrastructure.
I'll leave this post with a paragraph from Bicycling .com. "A 2015 report by the National Highway Traffic Safety Administration found that 70 percent of cyclist deaths occurred in urban areas. Only 3 percent of those fatalities took place in a bike lane. If you really want to make your road rides safer, joining your local advocacy group, or organizing one to push your city and state for better bike networks, is a great place to start. Simply donning a helmet is no substitute for safer streets".