I don't understand why or how a rough sketch of a system is patentable in the first place. The air traffic control system isn't patented, our system of roads an

I don't understand why or how a rough sketch of a system is patentable in the first place. The air traffic control system isn't patented, our system of roads and highways aren't patented, bike paths, trails, and so on are not patented. Patenting a system of automated "see and avoid" for autonomous flight is a maybe, but ultimately all such aircraft have to fit into a standardized system that cannot depend on any one patent. One company can't "own" the drone air traffic control system.