You drove and pulled up to the gas station to fill your gas tank. You exited your vehicle, opened your gas tank cover, grabbed and put the dispenser nozzle in. You also had to pay at some point.
How can you forget that the hose is still connected to your car when you drive off?
With autopay the payment is done automatically by reading a proximity device on the filling hole, with credit/debit cards you put the card in to activate the pump, not at the end of pumping.
Go out of the car, put nozzle on other side of the car, go back inside the car waiting for it to be done, assume a station worker took the nozzle out, drive, hear a station worker screaming, drive back to return part of the pump.