My understanding was that it determined the volume based on an assumed temperature of 15C regardless of actual temperature. To do as you suggest, wouldn't the dispenser need to know the actual temperature as well? When I worked at an oil company recently, I looked over the info on dispensers and underground tank equipment and there was no part or mechanism for measuring fuel temp.
PS - they are dispensers and not pumps. In the old days, there was a pump for each hose. Now there pumps are at the tank and maintain a pressurized system. The hose is connected to a dispenser with no internal pump.
Mike