From everyone else in your building? What's top stop the guy in 5B going "Hey... package... thanks" I see a huge uptick in stolen packages. Heck the drones themselves would make a nice parts source flying free over the city. Just have to pick off a couple of them now and then.
I think the point when this becomes in any way practical is really really far off. Interesting demo for sure but pretty sure I'll never have something delivered this way in my lifetime.