As far as I know there is no such thing as directional glass.

When you reduce the transmission of light by tinting or mirroring, you favor the bright side.

Say 25% of light passes through. Outside is bright, call it 100 on some scale. 25 will come through for the occupant to see. Inside is dark, call it 10 on some scale. 2.5 will go through for the passerby. Tint it to any percentage you want and adjust the light.

The answer to this one is a camera. Mount an inexpensive rear camera from the autoparts store with a screen inside, frost or tint the window however you want.