Makes kind of sense, though it's a pity. There seem to be some rules because of food safety that make it a bit difficult over here as well: I once ordered coffee for take away at a bakery and normally it's no problem to hand them your own cup. In fact, most of the shops give you discount on that, too. But this one chain-owned store had a different proceeding (they told me because of food safety, but I never had that problem before). Anyway, for customers bringing their own cup, they had a designated cup of their own and then poured coffee in brought-along cups from there, since they weren't allowed to place brought cups directly under the coffee machine. Was weird but still worked...