If there are kids kicking a ball around and it lands in your yard, are you legally obligated to give it back?
If it landed on my property they'd get it back, eventually. I wouldn't make it easy for them, though.
But that's just because I'm "bad".
Remember the self driving Dominoes Vehicles they said were gonna revolutionize the way they Delivered? They tested those little buggies here in Bakersfield. They did end up feeding every person that figured out that tossing a 4x4 under it meant...
Y'know how hunters like moose heads on the den wall? I've now got a mental image of some Mancunian chav sitting in his mum's council house with a big spliff and a range of delivery drone motherboards nailed to the wall over the gas fireplace...