The problem will be mostly ironed out before mass production and commercial use. The off chance that this indeed happens would be a pretty rare occurrence.

Or there would be work arounds for that specific model that fetches coffee. I'd imagine it would be like one of those small discs that pick up dust and cats ride around, but this instead fetches water or coffee from the coffee maker built for that robot. Then the center of the robot the cup is attached to raises up to about 3 feet for when you're sitting at the table and since hard wood floor with and open concept design is becoming popular it would make this quite feasible.