Because, if the store owner's business model is > People are welcome to offer items for free on my shelf space, but if they make money based off the items peop

Because, if the store owner's business model is > People are welcome to offer items for free on my shelf space, but if they make money based off the items people got from those shelves, then I get a cut Then, if you accept a donation because of such items, then you pay. Because it was stated up front and it's part of the owner's business model. As to how it effects the store owner. Let's say the store owner does not allow free items on their shelves at the moment. And they make enough money to pay their bills, plus a little extra. The owner decides to allow free items on their shelves, with the above caveat. They figure they will make less money overall (free items now take the place of items non-free item), but still make enough to live on. Only now, just enough, no extra. If all the people that give their items for free + donations decide not to pay a share of their donations, then the business owner does _not_ make enough to pay their bills... because the assumption of people paying that money was built into the decision to allow free items in the first place. So there _is_ a different to the store owner. Obviously, Google doesn't make "just enough to pay their bills", so the analogy is loose... but the concept of people following the rules that were set out at the beginning being built into the business model, and the decision to support that model at all, doesn't change because of that.