Drinks that normally get free refills do so on DDP.
OK Thanks. The "single serving" part threw me.
It's also to cover items that are meant to be shared by more than one person - don't know what kind of drinks they have that are meant to be shared - the only ones I can recall were in Vegas and were alcoholic.
Maybe bottled still or sparkling water, when included, to enforce an individual size instead of, say, a 750ml or larger bottle?