Judging from the pics there's hovering bicycle roundabouts everywhere in the Netherlands, but TBH I never saw one of those. And we don't have a different riding style, our cyclist population includes more than a couple of very select demographics, so the people with an "Anglosaxon" style are a minority here. Pretty much everyone cycles here including scores of people from accident-prone demographics like children, teens and the elderly. Anyway, Cycling is no doubt much safer because we eliminated the big hazards but I'm not convinced we have less accidents of the type bicycle helmets are designed for. Most typically simple falls.

Judging from the videos etc., the increased risk seems for an important part due to the fact that many cyclists have little insight in safety. There might be more to win by growing some common sense so people understand that riding without lights, salmoning and doing 20 mph in busy down-town areas are inherently unsafe behaviors.

All in all NL and DK prove the world day after day that bicycle helmets aren't important to bicycle safety. That's a fact.