Autonomous vehicles, AVs, will sometimes need assistance from a human operator.
This can be achieved on distance from a "control tower" that not actually is a tower like in an airport where a visual control is required. AVs have cameras around and inside and an operator can use surround screens or VR headset to take remote control over the vehicle if needed.
One company developing remote control for AVs is Phantom Auto https://phantom.auto/
One "control tower" could service one country.
If a passenger needs assistance he press the CALL CABIBUS CENTER button on the cabin display and a video call is established with an operator that can help.