What if you strip out the entire 'aggregation' and customer facing side of DoorDash/GrubHub/UberEats and rebuild them as complete back-end logistics services to the restaurants? You charge lower percentage of orders or just a monthly fee to help procure and pay the labor and route deliveries. Seems like that's the actual challenge for restaurants
DoorDash already serves as the back end for a number of other services.
But being a courier company is not near as good of a business model. The aggregation element means that they own the end customer and payment flow, which among other things increases spend since you discover new restaurants via the platform and can transact seamlessly with any restaurant on DoorDash vs giving your card info to each new place
More importantly, as a two-sided marketplace DoorDash enjoys network effects which are the source of its defensibility. If they were just a courier company, restaurants could just switch over when they found the next company that could deliver marginally faster or undercut them with VC funding. As a two-sided marketplace, the restaurants can't turn them off without losing all the demand coming through the platform, demand which is captured by DoorDash is because they have tons of restaurants on the platform, creating a feedback loop.
Chipotle has white labeled DoorDash for delivery in my area. If I open the Chipotle app and make a delivery order, the "track your order" screen says it's "Powered by DoorDash."
CloudKitchens is more the kitchen infrastructure for restaurants who only have a presence on delivery apps. They are trying to facilitate a restaurant model that is optimized for the delivery apps'supply chains rather than starting their own