I wonder how many of the commenter here have actually ridden a bike? Anyhow, one conveniently unasked question is "what do bike helmets protect the rider from"

I wonder how many of the commenter here have actually ridden a bike? Anyhow, one conveniently unasked question is "what do bike helmets protect the rider from" Well, it isn't collisions with cars. It is unlikely to be brain injury. It isn't jaw fractures. We know this because the lack of research in all these areas is almost non-existent. The best we can say is that a loss of control incident (not a vehicle collision) may be mitigated in some dimension by wearing a helmet. Pretty much all other assertions are just that, assertions with no basis in science. A single study doesn't count as basis. There is however a lot of evidence for risk taking behaviours on the behalf of drivers. That's why 39,000 people were killed in road collions in the USA in 2020. 45% of them caused by speeding, alcohol impairment, or not wearing a seat belt. Not wearing a seat belt is different to not wearing a bike helmet due to the extreme difference in speeds, collision dynamics and kinetic energy. Remember mv^2.