The argument of proponents used to be that it removes a lot of large vehicles off the street for small local deliveries… yes and onto the sidewalk. Makes no sense.
The density can go up quite a bit when you don't have a car needing to haul itself around.
Why car? In our city the delivery guys are using tuned e-bikes.
Or we could build walkable cities so people can, you know, just walk to the restaurant.
I don’t think there are proponents, just corporations with capital looking for a new way to extract and concentrate wealth away from individuals. The fact that it’s a robot on the sidewalk is an implementation detail.