First there was the humble shop. We were a nation of shopkeepers.
Then came the department store. These offered the customer everything under one roof. However, it soon became apparent that what the customer wanted were the shops they had come to know and trust. So the department stores offered to house these shops as concessionary units. This made sense to many shopkeepers who could relinquish some of the risk and cost of shopkeeping to focus on their product.
Then came the mall: giant shopping centres which offered a home for shops and department stores alike. For some traders, they were now a concession, within a store, within a mall.