Robotic jet tugs and fuel savings

Besides circling the airport it is my understanding that the biggest usage of fuel of airlines is ground operation. Having a jet idle on the taxi way for 45 minutes is a huge waste of fuel. (In order to keep the fuel/air mixture right in the thick, oxygen rich air near the ground, the turbo fan engines burn vast amounts fuel.) However, the major cargo shipping ports have an answer, since they have found away to automate the movement of containers, using robotic trucks. It wouldn't work as well for landing aircraft but for getting planes to the takeoff point it could be very economical to have a robot tug not only push the plane out of the gate but take it to the runway too. Then the pilot could start the engines, a few minutes before take off and the aircraft roll onto the runway under its own power.To keep the system safe the pilot and the tower would have encrypted control over the vehicle and both would have to agree on the route to allow the system to operate. In case the communication was interrupted the robot could be controlled via a hardwired manual system. The route taken could be controlled via in ground markers, and UWB based transceivers to double check the position and relay it to the tower. In the event of total system failure the aircraft could still move themselves.I realize the system wouldn't be cheap but with fuel prices where they are the savings and reduction in emissions would be worth it. A small amount diesel or LP versus a huge amount of JetA would have a huge impact.