why is there a poop deck on ships if not for pooping

They don't.

Really though people carry toilet paper in China because public restrooms don't have it.

Oh they do wipe. They preemptively decided to shit in public.

It's worse that they do wipe. They don't take their tissues with them and drop it on their poop and the wind starts terrorizing the local people cuz that tissue becomes a moving bio weapon.

i dont think they do.

usually its very unsanitory to shit in your crops, because you spread bacteria that is more harmful other people. its different from a cows dung feces over humans. E-coli being one of them, thats why they use manure of herbivorious animals over carnivores/omnivores, meat eaters have more potential to have parasites too, in the old ways. but they use synthetical manufactuered fertilizers to avoid the problems altogether.

farm peasonts that have always lived there at least for hundreds or thousands of years vs american farm peasants who have been there for like 320 years max, like peasant culture is more modern/new here than other countries

I don't know, I've seen grown ups pissing in the park in Shanghai, not somewhere deep in the bushes but right beside the pavement and buildings. That was not indoors, at least

its probably farm people vs city people, the latter has more etiquette than the rural folks. alot of rural chinese suddenly became RICH overnight, so they havnt adapted to proper etiquette.