For example they decide which hotels/restaurants to show in an area when you search. They won't show all of the nearby ones. They might show one that is 5km away and not one that is 100m away.
Once I was in a restaurant that was not in maps. I decided to add it to the map when I was home.
Turned out the place was in their database, but they just decided to NOT show it, even at maximum zoom level over it. But when I added it, they asked if it wasn't that other one that already existed.
Moral of the story: use openstreetmaps.
I have the same problem with my barber shop of all places. Even though I've been there probably a hundred times maps never shows it no matter the zoom level, I have to search it by name to find it.
My cynical view is they once said no to a promo offer for ads and are now punished for it.
This is my suspicion as well. In the end it is very dangerous to let google decide which venues get business and which get hidden completely. Eventually paying google maps becomes akin to protection racket.
Is it possible that Google legitimately thought there was only one business at that location?
edit: to be fair I just tried searching openstreetmap for "flowers" in a small town I'm familiar with and the results were bad. It zoomed into a two block area with a single flower shop even though many others exist outside of that area. Even in that zoomed in area I could barely see the flower shop on the map because there is no label/pin.