No safety steps are needed. The criteria should be whether the cost of the intervention results in more benefit than if that cost was spent elsewhere. If you're going to have no defined ceiling on additional safety measures, the obvious step is to stop bicycling and choose a safer form of transport, or to stop traveling.
Virtually everything can be made safer, including sleeping and breathing. You don't have to prove it. You have to prove its cost-effectiveness.
Is your argument that any small optimization is needed?
Any form of transportation could be made safer with helmets, presumably cars far more so than bikes. Hell, surely some number of people suffer brain injury after falling out of bed. Should we all wear helmets to sleep?
The discouragement of biking is a big deal in the Netherlands. They’d rather have everyone biking casually than a few dedicated speedsters decked out with the right equipment.
I assume he didn't - the point is asking people to wear helmets discourages biking. In practice it's overall healthier to not ask people to wear helmets.
Having visited Amsterdam once, I'm honestly a little surprised there are so few cycling accidents. The number of bikes is huge and the flow of it looked a bit like a controlled chaos.
The Dutch seem to have understood the street smarts and the unwritten rules of cycling (as applies to their environment) really well, so that probably explains it, along with a cycling-friendly environment.
Virtually everything can be made safer, including sleeping and breathing. You don't have to prove it. You have to prove its cost-effectiveness.