@oristarA,
Contrex, I've seen it either way. I don't think there is a hard and fast rule about it.
Ori, cooler's can be made out of many materials. The kind in the photo are actually very strong and light. They are insulated with foam wrapped in thick plastic sheath, or double hulled. They can with stand quite a beating, but for more strenuous outings many campers will use metal/aluminum coolers.
I had to look up bivouac, I've never heard that term. We (in Canada - as the terms change on every continent) would more likely say.. we are going camping, tenting, RVing, or boondocking - depending on where and how you camp, or your mode of transport and or sleeping arrangements.
I'm not trying to be condescending, I just don't imagine there are many camping areas in China similar to what we'd be used to. If I'm wrong, please tell me, I'd be very interested in learning more.
Camping is very popular in N. America, Australia and I believe it's becoming more and more popular in Europe. (I realize people camp in the UK...)
We have designated campgrounds, either publicly or privately owned, near lakes, oceans, mountains, cities, beautiful or historical sites amongst other odd places.. Sometimes people camp off grid, which means, unlike a normal campground, they are camping on government land far away from civilization or squatting... Usually it's not an area most people don't want to bring expensive rigs. These camper's have to supply their own power, by means of solar power or gas powered generators, water, firewood, garbage disposal, toilets and so on. Registered campgrounds may or may not supply all the above, some may be very primitive while others serve a more high brow crowd. But all will rent you a spot to set up camp. Some are nicer than others...