It doesn't matter if it's masquerading as a license fee, it's by all means a tax - it's required by law and you go to jail if you do not pay it and you have to pay it even if you don't want to consume their content.
In France we used to have the "Redevance audiovisuelle" which just like in German didn't use the same word. It was removed in 2022 but according to Wikipedia[1], this is what Germany is using. The french version has a European maps with the different sources of financement used in European TV broadcasting services.
Beitrag Wikipédia pages are available in other languages, namely Swedish and Esperanto. The meaning doesn't exactly match German's.
A specific "tax" just for TV/radio exists in many European countries, definitely not just Germany. And in general, there are many tax-like things out there where it's mandatory to pay them in specific circumstances and they go to a specific use.
