I have a number of theories:
1). These are the guys on the beach in dark glasses that love to oggle the girlies but don't want to be seen doing it.
2). The driver has either suffered a breakdown or developed some sort of social inadequacy and can't face the world outside.
3). They have developed some form of photosensitivity to sunlight.
4). These drivers like to appear "dark and mysterious" on the road.
5). These guys feel that privacy glass makes for a classier car. They are also likely to be the ones driving around with foglights on in bright sunshine.
Robbie.
