Lots of comments here of the format "every store does this."
No, no other store operates this way. Walmart and Costco do not have a little flea market of third party sellers inside their stores who run their own logistics. This would be more like Amazon being both an anchor tenant and owner of a mall, and requiring that every other store within the mall provide all their sales information, then rapidly evicting all the successful stores and replacing them with knock off stores that they also own.
No, no other store operates this way. Walmart and Costco do not have a little flea market of third party sellers inside their stores who run their own logistics. This would be more like Amazon being both an anchor tenant and owner of a mall, and requiring that every other store within the mall provide all their sales information, then rapidly evicting all the successful stores and replacing them with knock off stores that they also own.