The air flow plate reacts to the momentum of incoming air. Momemtum = mass time velocity, so less dense air will result is less plate deflection for a given CFM flow. It effectively compensates for variations in air density, but as a mechanical device, it has some inherent inaccuracies.

Mercedes tends to "overdesign" many things, at least back in the seventies and eighties. See my earlier remarks about KE built-in redundancy.

Duke