shop=greengrocer is valid also for shop selling only fair trade products, fruits/vegetables grown only in Germany or shop selling only fruits or only vegetables.

shop=fruit is also valid

but shop=fruit and other very specific top level shop-values has a big problem: it is not plausible for data consumers to support 10 000 or 50 000 different shop values.

and expressing full detail via more general shop= value and more detailed tags is not losing any info, while making easier to get at least some of info

(obviously, that is only suggestion given for consideration)