I would have probably asked before I took a picture just to make my intentions clear. But any shop owner who thinks they are going to be successful by trying to "protect" their shop from the realities of the marketplace isn't going to be in business long. People can shop online now, they can usually get a cheaper price and the shop owners can't stop that phenomenon. The only thing they can do is to differentiate themselves by offering something the online shops can't.
It called the free market - you have to offer something that customers value and trying to build boundaries around your business to create artificial value won't work anymore.