I should have mentioned, my father is German (from Mainz originally) and table manners were ... important ... around our dinner table. The experience at the Ethiopian restaurant certainly wasn't my first experience with the differences in German attitudes about dining. Eating with my father or my Oma and Opa was quite markedly different from eating with my Canadian farmer grandfather :-)
But leaving food on the plate wasn't acceptable in my house not because my father was German, but from my mother, too, because they grew up (or parents grew up) in a time when there often wasn't enough to go around and wasting food was a ridiculous and rude indulgence.
About the knife and fork thing, I believe that might partially be the difference between continental and Anglo-American style of handling the fork. [1]
But leaving food on the plate wasn't acceptable in my house not because my father was German, but from my mother, too, because they grew up (or parents grew up) in a time when there often wasn't enough to go around and wasting food was a ridiculous and rude indulgence.
About the knife and fork thing, I believe that might partially be the difference between continental and Anglo-American style of handling the fork. [1]
[1] https://theetiquetteconsultant.com/blog/2018/1/26/styles-of-...