I don’t know about Uber Eats, DoorDash, or GrubHub but SkipTheDishes here in Canada doesn’t use “loops”. Every delivery is one-to-one. You place an order, the restaurant confirms it, a nearby driver accepts it and travels to the restaurant to wait for it to be prepared, the restaurant prepares the food and gives it to the driver, the driver delivers it.

It’s very inefficient unless your goal is to optimize for quickest delivery and hottest food, which is what it is. However, there is one major efficiency it has over the restaurants paying for their own delivery drivers is that SkipTheDishes has a large pool of drivers to dispatch orders to from all of the restaurants. It’s like having a thread pool you can dispatch jobs to rather than having dedicated threads allocated to each work queue (which may end up idle a lot of the time).

Another thing you have to consider is that the drivers need to earn a living. If they only get one or two orders a night and spend the rest of their time waiting around then they can’t afford to do the job so they’ll probably quit. These delivery services ensure that drivers will have a busy shift because their scheduling systems don’t overbook drivers. That all goes out the window if you ask every restaurant to hire their own drivers.