Reading the question about Rich Wizards, Poor Muggles about wizard money and muggle money a contradiction about that came up in my head. In the answer of that question it was stated corectly that:
For the most part, there's very little that members of Wizard society want or need from Muggles. Property, housing, and food really seem to be about the extent of it for the vast majority of Wizard families.
Though most of the Wizards seem to have completely no knowledge of muggle money and how they work. An example of that is Mr.Weasly when he had to go with Harry to the Ministry of Magic by muggle transportation (using the subway) and have in mind that if Mr.Weasly doesnt know of how muggle money works with all the love and interest that has in them I think there is very little chance that others have better knowledge of that.
Some Wizard families grow their own groceries, though still they need other stuff that have to be bought like bread or meat etc. And for sure because of Gamp's Law of Elemental Transfiguration we know that food cannot be conjured.
In continue to that, I have to assume that Wizard families buy their food (groceries, meat etc etc) from muggle stores, for which they would need muggle money and ofcourse the knowledge of how they work (currency , etc). (never found a statement of butcher or groceries shop for example exhisting only for Wizards, even though in the answer of Rich Wizards, Poor Muggles the answerer assumes that there is such a place in the Diagon Alley for which there is no evidence of existance though )
These two facts contradict each other and confusing me. Is there a book mention that I am missing here or if not, maybe from other sources (pottermore or J.K.R interview) which states the existance of shops (to buy groceries, meat etc) exhisting only for the Wizard community? or else how is it possible that Wizards do their food shopping from muggle stores when they dont even know how muggle money works?