[snarg]

It's not about what is or isn't a public thoroughfare. It's about what is or isn't "a reasonable expectation of privacy." It just turns out that, because people are expected to walk/drive on streets, and people are also generally expected to have functional eyes, your front yard doesn't have a reasonable expectation of privacy.

[shadowgovt]

It's both. The problem is that the cost to just be passing by in the air has come way down, and that creates a new question of privacy that wasn't practical to worry about before.

(If it weren't being addressed by the cops specifically right now vis-a-vis warrentless searching, it'd have to be addressed by society eventually as we get into questions like "Who's eyes are on the camera feeds from all those Amazon delivery drones?").