[ghaff]

Well, Chinese food is also a commonly delivered item in many places--including but not limited to cities. So I'm not sure pizza is all that unique.

That said, a lot of food delivery is some high school kid driving his car around mostly working for tips. You start tacking on the costs of a large delivery-as-a-service company and your costs go up a lot without all that much economy of scale.

[johnpowell]

Even at a busy Pizza Hut a lot of the delivery drivers will help with making the pizzas, folding the boxes, and cleaning when not delivering. You can pay them X amount with fixed hours and they can stay busy the entire time.

With just delivery services there is a lot of standing around time.

[jschwartzi]

I was recently at an Indian restaurant with my girlfriend, and half to three quarters of the people in the waiting area weren't trying to be seated, they were delivery drivers waiting to pick food up. Most of them sat for upwards of 15 minutes.