Also, while you're right in that comparatively many people in Berlin are smokers (although that might be a commonality of cities as opposed to the countryside), they're still a minority of <30% [1], so more like 1/3 than 3/4 (it can feel like every second guy in the street though).
[1] https://www.abnr.de/tabakpraevention/daten-fuer-deutschland/...
The rules are not enforced.
I’ve lived here since 2008 and it is unlike any other major world capital.
I bet that even if a place managed to hide it from the public health authorities (they DO regularly do unannounced inspections anywhere food is served or made, after all), it would just be a colossal competitive disadvantage in most places. How strange that Berlin is different!