Pricing follows the operation
Territory size, order volume, average distance, operating schedule, service level and location all change what a delivery costs to run. Two stores ten miles apart can have very different cost structures.
That is why serious delivery pricing is built per store rather than published as one number.
The structures you will see
Most arrangements combine a partnership component with a per-completed-delivery component, sometimes with a setup element for launch work. The mix shifts with volume.
Questions worth asking any delivery partner
What territory is included? What happens on a failed delivery? Who talks to my customer? What documentation do I receive? How does pricing change as volume grows?