If you drive at night, the rear shade helps tremendously to avoid night light reflections if cars are following behind you ..... and ...... the rear window shades are thin enough to still allow drivers to see through the shades and notice that cars are behind you.
Years ago, when i drove my coupe everyday and at night, side windows were never a reflection or glare problem ... the former owner replaced both side glasses with metal R. C. Cola signs ....... not a bad accessory to have when Drive-In theaters were popular.