I tend to agree, and also because I don't think food delivery can be easily decoupled from the preparation (for ready-to-eat orders). I mean, restaurants have done it profitably for ages, but whenever one of these SV companies tries it, I hear all kinds of stories about how, unless everything goes right, the whole process becomes tedious an frustrating.
Like, the order's wrong, and it has to restart through Uber's whole system. And the runners can't look inside to verify the order because (legitimate) health regulations. And it just ends with an unsatisfied customer who has some credit on the app.
But I do think there is a way to SV-ize food delivery, like if they could get economies of scale to work for food delivery. Imagine this:
A restaurant knows at least one customer needs their dish to start prep at 5:30pm. The website indicates they're starting one then anyway, so you get a discount for ordering the same food to start at the same time.
Meals can be batched easily -- it costs them much less than N times to scale up the order to N servings or customers.
Ditto for (in urban areas) delivering to the same building or block. If they only have to stop once, they can offer a discount to anyone ordering the same thing in the same building.
This is exactly the kind of thing where it pays to be a broad platform that everyone's on, and has kinds of monopoly profits, and provides legit consumer value.
(Disclaimer: I registered a domain name suitable for this kind of service but haven't otherwise advanced it.)