It's milk-based drinks that are excluded, not Starbucks specifically. So it doesn't apply to things like chocolate milk, milkshakes, or milkshakes with a small amount of coffee in them.
This is just an example of a corporation buying out a local government.
I gotta question whether it's realistic to say that Starbucks bought out local government with it's infinite resources but McDonalds couldn't afford to?
I'd love to see the actual/official reasoning behind the exclusion though