The project you linked to is a perfect example. What does it matter if the phones allow you to control the robot from miles away if you have no means of feedback once it's out of your sight. How do you control something if you don't know where it is and what's around it?
If the phone in the robot has a camera, you could place a video call to the phone, so you'll be getting a visual feedback. So I'm pretty sure you control it miles away, provided, there is cell phone coverage.