There is a difference between gross margins on the food items in isolation vs the overall restaurant's profit margin. The point I was making to the OP, seemingly lost on you, is that there are plenty of costs that Uber (or a restaurant) must bear, such that earning a large gross margin on a specific item or service doesn't guarantee an overall profit.
The only thing I see lost is you. The complaint isn't that Uber is bearing costs, it's that they bare costs in the neighborhood of 3x what the delivery costs!
For a restaurant food needs to compete with paying for actual humans to cook it, paying rent, etc. all things reasonably expensive and costs huge money to scale.
For Uber owning a human's time for the next X minutes should be by far the largest expense because the other side of it is software!
If you understand how software works this shouldn't be hard to grasp... software scales for relatively nothing compared to human labor and rent!
The only way to break that equation is to squander your cut on overaggressive expansion. Overaggressive of course being defined as the point where you spend so much money drowning people who aren't using in perks and advertising that you end up having to squeeze restaurants drivers and existing users harder and harder to keep the ponzi scheme going...
So according to you, delivery companies have fat margins and zero marginal costs because it's all infinitely-scalable software. The only thing holding these companies back, then, from massive profits is "overaggressive expansion."
Very impressive. Your plan is impeccable, I cannot find any flaws whatsoever (keep in mind, however, that I'm a dummy who doesn't understand software). You've obviously cracked the code that has eluded the existing executive teams at GrubHub, Postmates, Door dash and Uber. I hope you have submitted your resume to all of them, clearly you are all set to be CEO!
What have I said that's incorrect, or where have I mischaracterized your statements? You wrote: The only way to break that equation is to squander your cut on overaggressive expansion. If "overaggressive expansion" is preventing profitability, why aren't any of the delivery companies reversing course and doing what you suggest?