"Here's your food," whispers the robot at the airfield restaurant in Gelnhausen, some 45 kilometres east of Frankfurt. "Please take the food from tray one." The guest complies, reaching for the plate full of steaming meat, gravy and mashed potatoes. "Press the screen to confirm," says a voice from the serving trolley. The robot concludes by wishing the patron a hearty appetite. Then the monitor's face with big googly eyes and a red kissy mouth smiles. "I'm a hard-working waiter. I'm happy to ser