The case count for Germany atm is very impressive, but we ditched masks in June, and cases actually plummeted after that, and only started to rise with the delta variant. We still compared to most have a low infection rate.
There is nothing to support the theory that shops are hotspots for spread, if that was true alot of supermarket employees etc, would have been infected, at a larger rate than average. However this has not happened anywhere.
You can cite 100 counterexamples when using this simplistic kind of reasoning. Covid numbers are quite high in South Korea and Japan which both have sky-high mask compliance, for example.
Isn't that part of the scientific process? Is there some other way to come to the truth aside from observation and examining variables related to the observed outcomes?
If you notice at the moment the corona numbers are high in Netherlands and Denmark while low in Germany.
Because Germany has kept more restrictions in place, in particular mask wearing in shops and transport.