Food delivery used to be arranged by source, and multiple orders per outing. A pizza delivery driver would usually do 3, maybe 4 orders in a run. Similar with other places, if they had enough business to justify a delivery driver. Good delivery restaurants would coordinate kitchen and drivers so neither orders nor drivers would wait long for the other. Pizza in particular is ideal for delivery, because most people want to let it sit for a bit before they eat it.

Food delivery as an external service from anywhere has poor coordination. Many restauarants don't get enough orders to have a batch delivery. Many food items need to be eaten right away, so the driver needs to idle at the restaurant for best service, which kills efficiency.