It can also be a septic system issue. A lot of septic systems either need specific TP, so it doesn't mess up the system, or no TP to be flushed so that the system can work properly.

In cities (anywhere with a sewer system), generally this isn't a big deal. Most North Americans have grown up in cities that were built after indoor plumbing and municipal sewer systems became a thing. So the system was built to be robust. However, many homes in Europe are older than indoor plumbing, and were adapted for it when plumbing became a more consumer-viable product. This is also why the hot/cold on European faucets is separate. The hot water was usually non-potable, while the cold was generally fine, due to early water heater systems not being sealed, and the exposure to external stuff and warm temperatures made it a very nice place for bacteria and other things to grow.... So the hot water was generally not safe for consumption, while cold was generally fine. So the hot and cold were usually separated to keep the bad things festering in the hot water, from getting into the cold water.

The history of all of this is actually rather fascinating to me... Needless to say, there's a lot of good reasoning that's not necessarily still relevant, for why things are the way they are.