A number of companies seem to have policies against in-store photography. Supermarkets don't want their competitors getting accurate data about their pricing. Usually, it's the ones that offer loyalty cards so they can track their customers more effectively.

I have no idea how a branch of McDonald's in the centre of a major tourist city expects to be able to keep any secrets but it may simply be a company wide policy. Someone should update them on just how small, cheap and effective actual spy cameras are these days. Not to mention phones.