1. Dominos does 2.5MM deliveries sure, but Dominos is a marketing company first, a delivery company second, and a food company third. Their products are purposely made to be sold enough to cover labor and ads with barely enough left over, but combined works with a franchise network.
Which means...
2. Most providers on the platform are really bad, if your restaurant is working with DoorDash it's because your food is bad and delivery is the only value add, see regards to In 'N Out vs Jack In the Box.
So that means they have to ditch their current form since...
3. Churn of drivers is insanely high since they're viewed as disposable. The pay is low after considerations, limited job security, limited upper movement, limited support for drivers. All because the margins are just not there at the level they're at.
Obvi, since people's habit of spending $20 on a $8 burrito isn't sustainable.
So Postmates and DoorDash all running faster towards being USPS before more down rounds to tackle last mile problem--with UPS/FedEx just chuckling on the side playing with their plane and ships and Uber playing with their trucks.
PS. Analog to this is https://gorickshaw.com, a YC company.