Have American satellites been designed to be refueled in orbit?
Have they been designed for automated, robotic service in orbit?
When did this start?
The Northrop (Orbital) Mission Extension Vehicle DOES NOT REFUEL the client spacecraft. It latches on to spacecraft that have almost exhausted their fuel and provides station-keeping service for them so that they can continue to generate communications revenue for additional years. An actual first full scale refueling mission is in development by NASA and Maxar to demonstrate the technology on the old Landsat 7 satellite. Early docking and liquid transfer in-space experiments were done by DARPA over a decade ago.