Joke's on you, the geometry of my toilet means that sit-and-pissers splash into the bottom of the seat so I have to clean the rim way more often than I used to!
You don't clean plastic lens spectacles with paper as paper will scratch the lenses, though glass lenses can be wiped with paper. Wood is harder than plastic.
Toilet 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.
Their children are furry and meow. But in all seriousness, I would consider it an engineering oversight for not considering how their product is being used in real households.
Even I have to clean up when I miss; which happens max, max, 95% of the time.
You miss a max of 95% of the time? 🙃 On a related note, most people are bad with percentages.
the only thing I've ever had to wipe off the seat is condensation. I've no doubt children find a way to get pee on it but anyone with two braincells to rub together knows the seat moves out of the way