>Besides, it's not invisible despite calling it that. It's visible in the visible spectrum and hearable in the human hearing range, which means that you can build detection and tracking systems in those wavelengths instead of pretending that its invisible because its hard to detect at radar wavelengths.

There have absolutely been programs to reduce the visual signatures of aircrafts. Yehudi lights, COMPASS GHOST, BoP, etc. Don't get your information on anything from Musk.

Good point but all these things can be fitted on a drone too.