Sure, helmets would make cycling safer. Helmets would also make walking on the sidewalk safer. But I bet you don’t wear a helmet there. This implies there is some level of risk you’re willing to take before you wear a helmet.
My theory is that cycling in the Netherlands is safer than it is in most countries. Just some factors:
- People mainly cycle for transport, not for sport: you sit upright, you go relatively slowly
- Every car driver in the Netherlands is also a cyclist sometimes, so people know how cyclists behave and respect them
- Cycling is everywhere: you don’t encounter cyclists only in the center of big cities, basically every road except (often, not always!) highways will have cycle paths in parallel so as a car driver you encounter cyclists everywhere and anywhere
- The bicycle infrastructure is fantastic: if possible bike lanes are separated from car lanes by greenery or trees or something, bike lanes don’t cross right next to intersections (so you’re not in the blind spot of a car making a turn - the car already turned and then crosses the bike path) etc.