Why doesn't Barista Oatly come in bigger carton?

I work in a cafe and think choosing oat milk is a great way to make your coffee order more sustainable but I noticed that Oatly comes in a carton half the size of the dairy milk we use. Surely offering cafes bigger cartons of Oatly would help to cut down packaging waste and make it an even more sustainable option, can't see any down sides to this!