Here in Japan, I've never been to a place where you don't flush your toilet paper. In fact, they sometimes run into the opposite problem, with tourists not knowing you're supposed to flush the paper (https://www.japantimes.co.jp/news/2015/08/26/national/kyoto-...). Part of this might be because you're not supposed to flush sanitary napkins or anything but toilet paper, so there's often a bin next to the toilets for disposing of those, which I could see as confusing to someone who comes from a culture where you don't flush toilet paper.

Not uncommon in Europe either. Especially in non-renovated parts of old cities or middle-of-nowhere kind of places. Old pipes just can't handle too much paper.