>"The microphones in every nook and cranny are merely filtering a public good, the air. You should know that when you vibrate the air with your vocal chords to make the sound of words, you're willingly broadcasting information patterns in quadrillions of particles in the air. It's not our fault you're so stupid about your security."

Don't be dense. Letters are easily intercepted and read, but we still expect that the government is not doing so because the constitution forbids that sort of behavior and the judicial branch is supposed to protect us from it.

You're conflating privacy with security. Security requires encryption, etc... privacy exists in the absence of monitoring devices.