Helmets are designed to protect riders from bike crashes, not from cars.

Dutch commuter bikes are slow and upright, and many have a low top tube and are thus very easy to hop off of— a 9-12 mph bike crash is not unlike slipping while jogging, whereas a 18-35 mph crash on a road bike is a lot more risky. Lower-speed cycling is enabled by Dutch land use which does not require many long-distance trips: https://www.peopleforbikes.org/news/best-kept-secret-dutch-b...