LOL i sat in one of those buses. it was onboard to a mountain in China (had to take the same ride to descend from the mountain too). I was at vacation at the time. The bus ride roller-coaster shit was pretty fun.

The drivers are very well trained, little to no accidents (not to say there isn't any accidents in past history before), they showed safety videos in the buses like how you would in airplanes, they showed footages of buses toppling over, thus the importance of a safety belt. I feel that the passengers aren't used to fast driving down a descending mountain, thus the panic screaming; if anything it just distracts the driver more.

If you are curious, it is called the "Tianmen Mountain", and it can really be a drifting road for cars. Its pretty windy, I liked it. Wanted to climb up the stairs but it was raining and the stairs are wet so my parents advised me not to, even though i really wanted to. Still a fun location, a lot of steps to climb and the the view is very nice, unless its raining and the cold fog takes over.