Hyperreality

1. The German language doesn’t work well with pun based humour. This is the kind of humour English speakers are used to.
2. They do but you need to be able to speak German to understand the jokes they’re making. Understandably, it’s hard to be funny in a second language.
3. IME German humour is often incredibly dry, deadpan or even anti-humour. In the past I’ve experienced Germans making jokes, and British people thinking they were being deadly serious. Eg. “An Irishman, a German and a Brit walk into a bar. They order beer.” Expressionless face - shit example, but you get the idea.