@sic_semper_tyrannis The Wikidata tag should link to the entry about the feature itself, so it will be different for each particular location (so, as most locations won't have a Wikidata entry, no Wikidata tag can be added in OSM). The brand:wikidata refers to the Wikidata entry about the brand, so it's the same for all locations under that brand and all locations can have the tag.
See this location, for example: https://www.openstreetmap.org/way/220089987#map=19%2F41.892868%2F-87.631575
Wiki: https://wiki.openstreetmap.org/wiki/Key:wikidata?uselang=en