If you think delivery is unsustainable because cars cost money, I got news for you: You live in a bubble, and it's the cars that are unsustainable.
Outside of the car-centric world of US suburbia, most of the western world is actually doing deliveries on scooters and ebikes, which are very quick to navigate medium-to-high-density cities and can do several deliveries per trip.
I've ordered a lot on Takeaway, at least once a week on average. The last time I saw somebody pull up in a car was during the COVID lockdowns, and I suspect it's because there was basically nobody on the streets.
The business model is broken, because car-centrism is broken. In the civilized world, things are ok.
Either way, fuck Uber. There's better alternatives.