As a German living in the US since 10 years and as someone enjoying driving above 200kmh when visiting family at home I can say that multiple factors play a role with street safety and speed is probably a smaller part of it.

It is quit simple...In Europe -by law- the one who is merging has to yield for the ongoing traffic. It is just a curtesy to drive over (or slow down/speed up) and to let other merge into the highway. And I would guess the majority of drivers know this.

Hey, I am from Hameln (45min from Hanover airport away and at the moment I live in beautiful Indiana). I know in one of our neighbour villages is a private collector of old VW beetles and he also has a private museum. Maybe you are interested to visit it because it is just 30min south of Hanover airport (in Hessisch…