because I need a doc's certificate to show my employer?
As for hanging around in a waiting room, I agree it's insane on many levels. I usually ask very directly if it's okay to come back in a while instead of waiting around. Though my primary health care provider has people with a cold wait outside in their garden, which is much better if you come prepared.
https://www.dak.de/dak/ihr-anliegen/corona-telefonisch-krank...