If you give me your old TV for free and I use it, we both are happy. If you give me your old TV and I turn arround and sell it for 400$, you're probably not happy, despite you not getting any money in either case.

Or, in case of your store example: The store owner does not have a store "for free". He still needs to pay the bills and be there. By suddenly earning money with his goodwill you're basically monetizing the space he is gifting to you.