Have you considered what happens to that business if DoorDash is forced to reclassify its workers as employees? A delivery business is particularly sensitive to classification because of all the expenses that drivers incur, namely those associated with the use of their vehicles.
Do a Google search for "delivery driver class action" and look at the Glassdoor reviews for some of the companies in the space, this one included. Instacart has already been sued and it's only a matter of time before all of the major players are forced to defend their models in court too. You don't just get a free pass because you build an app, raise a bunch of money from VCs on Sand Hill Road and try to position a basic delivery service as a technology-based communication platform.
I wouldn't turn to DoorDash to deliver live lobsters to me from Maine overnight, and I wouldn't turn to Fedex to get me food from down the street. Those are very different businesses requiring very different infrastructures. Therein lies the problem for DoorDash: they are not that different from Uber. They have similar core competencies, but Uber is vastly better known and financed.
Uber, DoorDash, whatever, they're services glued together with server-side logic and mobile apps.
Fedex, UPS, and I'll even lump Amazon in there. These are logistics powerhouses. Their physical world equipment isn't a liability, its their advantage. Fedex and UPS have knowledge on how to manage a fleet of hundreds of aircraft, thousands of long-haul tractor trailers, tens of thousands of local delivery trucks, and hundreds of thousands of employees.
Your app does not have that. You have users. You have VC money. And while you might think you're more agile than logistics dinosaurs, they have the upper hand. Good luck.