It seems like a violation of the privacy of other customers, too. Everywhere your food stops you can surmise there was another delivery.
In cities this shouldn't be easy to track anyway. And then you could also jsut follow the Uber bike. Don't think that the fact that someone ordered food is private (what they ordered might be).
This is particularly useful for me as I then know when to listen out for the door, and I've confidence in the ETA knowing they're just a street away from me.