You could already have pure vending machines serve what baristas serve you at Starbucks, Costa, whatever, you would get exactly the same product and it's close to what happens in reality. But people want a coffee shop experience, not a vending machine experience so I think moving robots will be a thing (unless people really insist on interacting with humans)
Sometimes, the service is part of the coffeeshop/bar experience, but seeing stuff being done is a fairly minor part of that, at least for me. Instead, it’s a quick chat or a recommendation, neither of which a moving arm really provides. You might be right that the apparent labor, either by a human or moving arm, also masks the (large) margins on a coffee drink. I hadn’t really thought of that as “the experience” (vs comfy chairs, decent music, and a pleasant murmur of other conversations) but you might be onto something there.
However, I think the main reason vending machine coffee isn’t popular is because it’s historically been pretty bad. The newer ones (Nespresso, etc) do make decent coffe, but you can still get some vile sludge at hospitals and rest stops.