It's very helpful to be able to tell if someone is looking your direction, as a driver and even more importantly as a pedestrian.
It's either not recommended or illegal here for that reason. We live in a very hot place and I would much like to be in a darkened space most of the time, but here we are.
I keep getting ads for facebook groups that have a picture of a bunch of old cars with a caption like "All metal bodies, not a seatbelt in sight, and we did fine" and they definitely did not do fine