01·
6 days agoToilet paper is wood, while the seats are plastic. Wood is a 2.5-ish on the mohs scale, and plastics tend to be too. So they scratch at a 2.5 with deeper grooves at a level 3, even on a micro scale. The alternative is to use ceramics for the seat, but the fragility means one rough drop of the seat and it could shatter. Metals are generally no better.
I almost instinctively downvoted you