When I went off to Wales last July, I had approximately 10 heart attacks. I got caught with a "back log" and soon found out why, in the middle of nowhere, there was traffic.
Two coach buses, full of tourists no doubt, tried to pass each other on roads as narrow as the ones in the pictures. Some would give way and back up, slowly. All the cars behind the one who gave way would, too, back up.
Because the passenger side was on the right (not on the left as is in the U.S.), I was spared the view of hundreds of feet below.
I must say: because the roads were slightly more treacherous, people paid more attention to driving with caution!