Hey! It was understand for a long time that this was the case too. It first came to my attention after seeing an Osmose issue mentioning it, so I looked into it further. Reading over the wiki page (https://wiki.openstreetmap.org/wiki/Tag:amenity=fuel#How_to_map), it states that the amenity=fuel tag should be a node at or way around the fuelling area, and later goes on to say that a roof can be added as a part of the surroundings rather than part of the fuelling station. I had a look at Overpass before too, and it seemed that tagging them as the same object is fairly common, but is far more common to have the fuelling area separate from the roof. It makes more sense to me now to do it this way as the roof and fuel station aren't part of the same thing; fuel stations just almost always have a roof. Please let me know if I've misinterpreted this though, or whether there is a resolution on which way is preferred.