Most restaurants didn't offer delivery so there was less competition and the ones that did could keep in-house drivers busy. This meant only half the trip (restaurant->customer) had to be completed after the order was made. It also meant the driver-ready-vs-food-ready problem didn't exist. The cuisines that offered delivery were also those optimized for delivery. Pizza and American Chinese travels much better than burgers and fries. Not only do they stand up better to sitting between being made and consumed but it's easier to count how many pizza boxes there are than make sure the burger also got its fries and side salad.