Ok interesting ... It's a must here in Oz I'd say, light is much brighter here and winters not so severe so more freedom to tint windows here I suppose
Different conditions, different rules - which suggests an element of common sense on the part of the rulemakers.
There are plenty of dull days here in the UK where you need every bit of visibility you can get. I'm having one this morning in Bournemouth.
As Maxi says, sunglasses take care of the rest.