If it hasnt been done yet, probably is for practical and regulation reasons. How many things are there that require a drone to be flied carefully? Roadworks, trucks, people on the street, renovations. Second, it's not hard to take down a drone, so if you're a criminal you'd start stealing drones with packages in place of simple packages.
Third, drones must be able to lift and transport boxes of different sizes, which can be not trivial, given wind, possibly being hit by this or that.
Fourth self flying is still not in reach, suppose you try to deposit and the large dog comes to see what happens in the backyard. Actually having 10 people remotely flying 10 drones is not so cheap.
As for regulation, I suspect there's plenty of people who don't want drones in the neighboorhood where their kids are walking and cycling, for security reasons.