Every indoor cat uses a litter box. If you walk into any pet store, you can find a wide variety of different types of cat litter including shredded up old newspaper or litter made from corn.
Yet in the early days of cat ownership, people used to use sand. Over 71 years ago, Edward Lowe created Kitty Litter and then had a hard time convincing cat owners that litter was superior to sand. That just shows how ingrained and resistant people are to new ideas, which cats readily accepted with no hesitation whatsoever, so that tells you who’s really more intelligent.