you should be driving slow enough that your braking distance matches your line of sight. I think most people do, especially in dense fog.

there are plenty of cities with great transit, just not in the states

People slow down in dense fog, but they slow down to see taillights distance which isn't enough for anything unlighted. People don't slow down for sun glare - that would be dangerous as the car behind you isn't - instead they assume there is nothing there, or they can figure out something is happening from the other lanes that aren't in the sun glare.

Even in cities you consider to have great transit there is room for improvement.