This falls under the "One feature, one OSM element" principle. A shop tag represents a business. If each building has a shop tag it implies that each is a separate business.

If you're using building extracts, you can use the building tag to denote its purpose, e.g. building=storage. Unfortunately there is no easy and reliable way to associate a building with a business.

https://wiki.openstreetmap.org/wiki/One_feature,_one_OSM_element