I know, but those wielrenners (wheelrunners) change into spandex, get their special drop bar fast bike out and ride through the city traffic to a road where they can practice their sport. The difference with me when I ride my bike to the soccer pitch is that my means of transport isn't my sporting equipment at the same time. When it's hot they often only put their helmet on at a traffic light at the edge of the city. If a fietser wears a helmet, it's a fresh foreign student, a tourist, a child younger than 8 or a parent forced by the child to give the right example.

It's actually the wielrenners now, the sports cyclists, who are the current biggest concern in safety for cyclists, they're also involved in road rage a lot, with fietsers mainly, but also with motorists and pedestrians. They don't always wait with racing until they're outside the city, and are often racing outside the city where there's just not enough space or they don't behave well enough while racing on a road while there are fietsers or motorists. I'm not suggestion that this is caused by them often wearing helmets nowadays, but they generally lack the friendlyness and relaxed state of mind of the fietsers. Conflicts are caused by difference in speed and state of mind, not by the different choice of contraption.

Nor is the Netherlands. If I bike 2 hours to the West most people speak a different language (they speak Dutch to, but often not as their first language), if I bike 2 hours to the east people there speak another different language. You'll find much more differences and often big and very old differences within very short distances, especially if you cross national borders. These days, both Germany and the Netherlands have a cycling culture, and they are influencing eachother, but these are completely different cycling cultures.