One thing aerial drones can do that delivery guys can't is access a fenced back yard. Instead of dropping it off on the front porch, they can drop it off on your back patio.
The 'not at home' delivery is the most confusing to me. I can't imagine they'd get very close too the door. They definitely can't 'hide it inconspicuously' behind something. I guess even when you are at home, they can't really knock on the door. So I guess it's just the middle of the yard every time.
At least the backyard would be better.