Do you agree that there's a difference between collecting information from spherically-broadcast radio waves, to which most building walls are nearly transparent, and collecting other electromagnetic waves by putting a detector in a place where most people wouldn't assume it would exist? I'd argue that using opaque building materials to block emission of radiation in directions that one might an observer to be located shows a clear intent to establish a degree of privacy, and that someone flying a quadcopter into unusual places to take advantage of holes in peoples' reasonable expectations should be counted as a violation.

The types of radiation that you're comparing have two very important differences that influence people's expectations: First, they're blocked by very different sets of substances. Second, we've got a detector for one of those ranges built into our heads. I don't think it's reasonable to treat the two segments of the spectrum in the same way.

I expect vehicles to drive by my home. I expect people in those vehicles to have wifi devices that can see the broadcasts from my AP. I expect their devices to capture that data, possibly store it, and possibly transmit it to another device. I think it's unreasonable to assume that someone won't do that. I don't have a strong argument for how capturing and publicly indexing that information is harmful to me.