Interception is a real problem though, especially in high-crime areas. You could reduce it with some sort of hardened container which can be opened only with a certain code.
Any container that is sufficiently "hardened" enough to stop any trivial access attempt would also be much heavier/larger (or have a smaller internal volume) - which would require a larger drone or a shorter distance. And short of carrying a safe, there's probably little you could do to prevent someone from getting at the goods.
Interestingly enough, the country that is likely to allow the use of delivery drones into regulations is also the country with the highest number of guns-per-capita.
If they drop it next door, they note which house they dropped it at and also have a signature to show someone actually took it.
The point is not to show that a particular person received the package, but that someone received the package. 99.9% of the time that's enough. If it wasn't and was impacting their bottom line, they'd have started taking photos of recipients by now.