Why is it that people don't see us? We all ride with headlamps on nowadays.
Could it be the 'Camoflage principle'? Theory is that a person wont register that they're seeing something if it isn't the shape they expect. Remember those jagged black/grey/white patterns that used to be painted on warships? They were supposed to break up the outline so someone scanning the horizon quickly,eg.through a periscope,would not register the outline as a ship.
It follows that someone not familiar with bikes would only register the shape of a car,especially if the idiot has a mobile phone stuck to thier ear!