In my experience there is really no way to know if the listing shown on the map is the only one or not. No matter how much you zoom in, some info is never shown.
I noticed this when I was trying to add businesses that were simply not visible on the map, even when extremely zoomed in to the building (and also no other POI showing up for that building). When clicking submit, I got the 'Did you mean this?' screen indicating exactly that POI...
I live in Saudi Arabia, and many places here are marked wrong even from the companies itself even in searches, how can we fix it as a local guides, and these days there is massive construction is going on in KSA, so every week there is new diversion in the local areas too, how long it takes for google to recognize that.
2022
