Why do black Americans get to be referred to as African-Americans?

I'm Dutch, and the Dutch are most commonly referred to as Germans in America. Why do I never get to say I'm offended by that?People from Africa can just say they're American, going for that not every black guy in the US is African, not every white person is German. And when a lot of people get offended by being referred to something else then what they are, I can't say I get offended by being referred to as a German without people calling me racist.<br><br>Edit: I'm sorry for my poor English in my previous posts, I'm a little bit stressed out rn.