When I was a wee lad our dog knew the milkman and would let him come inside and put the milk in the fridge if nobody was home but would stop him at the stairs if someone was home. Maybe we just need good dogs.
As for the Amazon delivery to the trunk of my car. I commute by car so if my car is there then there is an excellent chance that I'm also there so why not just hand it to me? I'd also hate to order eggs from Amazon's Whole Foods only to find them in the boot of my sedan a week later.