Christof quoted Movement by Thalia Verkade
The idea of a 30km/h limit came to us from Germany. Put a 30km/h sign on a German road and the locals will stick to it. It’s not the same here.
— Movement by Thalia Verkade (Page 188)
According to André Pettinga. But let me assure you, almost nobody actually only drives 30km/h here in Germany, at least not nowadays. Traffic rules are more and more a mere suggestion to German drivers.