Oh theres lots of things stopping a drone delivering a package to my porch, including but not limited to me, I dont want Amazon's drone blowing junk all over the place on my front porch, messing up door decorations, flower pots, whatever it is. Getting caught on a branch, a gust of wind blowing it into a column and causing property damage, my dog grabbing it (my dogs catch birds in the yard, they will certainly hunt this thing). I know the ideal scenario from drone delivery is magical but reality is had, same with autonomous vehicles.