Seats in buses in South America are very comfortable. Especially, "Cama". Even "Semi-cama", which is not as good as "Cama", is very comfortable. Even the buses in less developed countries like Peru have comfortable seats. And the seat in a train in Chile was comfortable as well.
After I came back to North America, I found that the seats in buses and trains were very poor and uncomfortable. I can't believe that I had thought that they were comfortable before going to South America.
By the way, unrelated but I saw people making a call from cell phone in a running subway in Chile and I think Argentina, too. But in North America, there is no signal in subway.