I don't think DoorDash has to be less efficient for traveling than pizza delivery.

With pizza delivery, you have to drive to the person's house then back. So you cover the same road twice for a single delivery.

But with DoorDash, theoretically, then could see there's an order from A to B, find a driver near A, have the driver deliver to B, then match that driver up with an order from near B to near A. So the driver could do 2 deliveries in a single out and back trip.