Comment by ggreer
An 8,000lb van will be using fossil fuels and emit particulates from tire and brake dust. Unless it was incredibly efficient and electricity for the drones was coming from coal plants, the van would emit more pollution.
But the biggest harm is people getting hit by vehicles. Delivery drones are much smaller and don't spend nearly as much time near people. Since drones can deliver stuff more quickly than large vans, they also substitute for individuals driving to a store to pick something up. So the total risk to pedestrians is even less than you might expect from eliminating many van deliveries.
I'm not so sure that the numbers will bear out what you sketch here. If we assume a drone flight per package and we scale this up to get rid of all of the delivery vehicles the number of people hit by and killed by drones will rise substantially. Drones are immature tech at best and a 5 Kg drone will put you in the morgue on impact with a greater likelihood than an accident with a delivery van. Gravity has no brakes and a drone isn't going to be able to refuse its imperative when the tech inevitably fails. I think you have to watch out not to be so 'anti' one thing that you end up with another that is as bad or even worse. Maybe the solution isn't drones and not delivery vans either.