nothing is stopping drones from say, ascending to 350 feet for the majority of their transit, and descending to 20 feet for the final final leg.
as far as i can tell, public roads are fair game.
i'd also envision a purchasing interface that lets them know where you'd like your package delivered on your property, and if you're fine with the delivery drone entering your airspace. I'd also envision you dropping a highly visible visual reference for where exactly you want your package set down.
alternatively, if that 350 foot climb is too taxing on them drone batteries, make a drone elevator