The Wiki says "You should tag the laundry area with shop=laundry, and you can optionally tag the individual washing machines with amenity=washing_machine."

I wasn't the one who mapped it, but I can see how someone who wants to map a laundry room with multiple washing machines shared by a whole apartment building or housing estate would come to the conclusion, from reading the wiki, that shop=laundry fits better than amenity=washing_machine.

Of course the Wiki also says "Never use for washing machines that are not available for public use, due to verifiability and privacy concerns." so amenity=washing_machine access=private would contradict that.

Maybe we need a better tag for "room with multiple washing machines shared by an apartment building or housing estate". Maybe under the room key instead of amenity.