This is a photo I took when I first lived in China in 2002, in the southern province of Guangdong: a bus with metal seats:
As you can see in the photo, the seats are entirely made out of metal (stainless steel from memory), rather than traditional seats with padding.
It was a little uncomfortable to sit on, although given this was in the tropics, the seats were probably cooler than padded seats – it gets pretty damn hot there. Having said that, I’m sure the primary motivation behind the metal seats was more to do with the ease of cleaning.
I’ve been on a lot of buses in China and the vast majority have padded seats very similar to what we have in the West. I’ve only ever seen these buses with metal seats in Guangdong.
You can also notice that in the front half of the bus there’s only one row of seats in each side of the bus and plenty of room to stand. Buses in China can get pretty crowded – although there weren’t many people aboard on the day of the photo.