Of course, you can arrive at the $20 just by thinking, "okay, I need someone to go do an errand for me, they'll have to drive to the restaurant, wait there for 15-20 minutes, and then bring it back... so it'll cost $15 for the hour of their time plus a few bucks of overhead for the platform plus a few bucks of messed-up-my-order insurance..."
Which gets us to 5 years from now when the DoorDash killer comes out, it'll be called Kourier or something starting with a K, and it'll start with trying to give Target a way to call up some extra trained Target employees, but they're cross-trained in packaging orders for K. One person will pick up 10 carefully-packaged K-orders, take them all to the central delivery hub, they'll get sorted into driverless cars that plot through some neighborhood some 10 stops, it'll be marketed as a real Amazon-killer and fly under DoorDash's nose -- InstaCart might balk, but DoorDash won't. Until they reveal some pizza-delivery partnership and suddenly within a year every restaurant has some K-employee working for them, whose job it is to batch orders down to the bikes that come by.
Sure, delivery times for Kourier will be 75, 80 minutes long at first. People won't mind because you pay $4 for delivery instead of $20. And Doordash/Amazon won't die, Amazon will just buy Kourier and DoorDash will focus on more rural locales.
I'll be disappointed if it isn't like Snow Crash (1992):
> The Deliverator, in his distracted state, has allowed himself to get pooned. As in harpooned. It is a big round padded electromagnet on the end of an arachnofiber cable. It has just thunked onto the back of the Deliverator's car, and stuck. Ten feet behind him, the owner of this cursed device is surfing, taking him for a ride, skateboarding along like a water skier behind a boat.
> In the rearview, flashes of orange and blue. The parasite is not just a punk out having a good time. It is a businessman making money. The orange and blue coverall, bulging all over with sintered armorgel padding, is the uniform of a Kourier. A Kourier from RadiKS, Radikal Kourier Systems. Like a bicycle messenger, but a hundred times more irritating because they don't pedal under their own power -- they just latch on and slow you down.
The $8 burrito is listed on doordash’s website for $11 + a delivery fee they were waiving for a first order (not sure what it would have been).
And while tipping is technically optional, it's de facto required. The driver will see the total pay for a delivery before they accept it, and if it's too low, they'll reject it, and DoorDash will offer the delivery to another driver. If you don't tip, then your delivery will be rejected until it reaches some driver that's gotten desperate. By that time, your food will likely have been already made and sitting and waiting for 30 minutes.