I don't tell people what they should be doing. Everyone so entitled to tell others how they should go about their lives. But there you go: you should try to understand my argument about these things moving in between the traffic.

But it's interesting you mention a bicycle license. In the 1990s I did one in Poland as a young teenager. It was called "karta rowerowa". Not exactly a license but it taught me about traffic rules and probably saved me from trouble. It was worth it. Some cyclists in Aachen could make use of something similar, maybe they'll know that cycling 5kph in the presence of the StVO VZ 277.1 just aggravates everybody.

Furthermore, I have learned today that in Poland until the age of 18 one is required to have the cycling card (karta rowerowa), or a moped driving license. „Karta rowerowa” is a one day training where one learns traffic rules, signs, and proper technique in navigating the traffic. Of course barely anyone checks for it. But if one gets involved in an accident, there will be financial and insurance consequences.

You don’t need special skills to drive a car.

A big part of licensing is that you can take it away. Cyclists and scooter riders often ignore traffic controls that apply to them. We ignore it because the likelihood and impact of injury to others is low.