Statistically, you are much more likely to die or be injured in a car crash than on a bike, so surely we should mandate helmet use in cars, right?
That is very faulty logic.
In a modern car with a person seat belted in, there is very little for a person to strike their head against (which is what a helmet protects against). The airbags are there to protect you from striking your head against the steering column or the side of the passenger compartment.
On a bike, there is nothing protecting you from striking your head against something.
When I was doing neurosurgery, I saw lots of head trauma. The head trauma for bad car accidents was more diffuse axonal injury caused by rotational or deceleration forces that a helmet would not protect you against (your head isn't slamming into anything). Whereas with bicycle accidents it was more impact trauma and skull fractures and resulting brain injury (which a helmet would have protected you against).
Source: Neurosurgery resident at a Level 1 trauma center.
Arguing on this line is pointless. You can use this line to justify any number of mandatory safer features. The goal should be to drive an adoption of clean, non congestive, personal transportation, and the primary drivers for this is cost and convenience. Mandatory laws requiring stuff is counter to this.
The simple fact is, in every place where cycling is normalized and not a deviant behavior for weird lycra-wearing dentists or people with DUIs, almost no one wears a helmet.
Mandating helmets is a failed policy if the goal is to reduce reliance on cars, and to make cities safer for everyone.
That's not the goal. The goal is to reduce head injuries. Mandatory helmet laws are effective at achieving that goal. If part of that reduction is simply discouraging people who would not ride a bike safely from riding a bike, that's not necessarily out of line with the goal.
…in the short term.
In the long term, if they prevent cycling from ever becoming a viable alternative to driving, then they’re still worse.
If someone is interested in trying a bike from one of those sharing locations, but they don’t have a helmet, they won’t try the bike in the first place. Especially if a city law makes a bike-sharing app “validate” that you’re wearing a helmet, to enforce the law, before giving you a bike.
Fewer people try the idea of riding a bike around their town, so there’s more pushback against improved cycling infrastructure because “it would never benefit me”, so there’s less infrastructure investment.
Continued ad nausium, cycling is less safe due to the limited number of people who are willing to advocate for safer infrastructure in the first place, which makes a much larger difference to safety than helmets.
That’s the idea.
There's resistance to improved cycling infrastructure because there's resistance to improving any infrastructure, no matter how critical, and the overwhelming majority of people don't see a massive rework of the entire transportation system to shift away from cars as a realistic possibility even in the moderate to long term.
If most cyclists wear helmets, why do you need to mandate it?
If most people refrain from stealing, why do we make theft illegal?
If most houses never burn down, why do we require smoke detectors?
2. Because it causes disproportionate harm to other people
3. I’m pretty sure that law isn’t universal and probably depends on city codes.. Regardless, if studies showed that requiring smoke detectors was burdensome enough to decrease the amount of new construction, to the point that it could be detrimental to society, then we should reevaluate that law.
"Pre-law surveys counted 6072 child cyclists in NSW, 3121 cyclists (all ages) in Victoria; and over 200 000 cyclist movements on two key routes in Western Australia. Equivalent counts a year after enforced helmet laws showed declines of 36% (NSW), 36% (Victoria) and 20% (Western Australia). Sunday recreational cycling in Western Australia (24 932 cyclists pre-law) dropped by 38%. Increases in numbers wearing helmets, 1019 (NSW) and 297 (Victoria) were substantially less than declines in numbers counted (2215 and 1110)."
In other words, Victoria started with 3121 cyclists, gained 297 helmets and lost 1110 cyclists.
Are you sure you didn't misread that 4% figure from a source that actually said 40%?
Needless to say, a 20% reduction in head injuries from a 40% reduction in cycling doesn't seem like a very good deal to me.