I worked at a Japanese company here in the US for about 10 years as the network engineer. We had this same problem. We were always getting new shipments of Japanese interns every month or so. They were always breaking the seats and tracking mud all over them. They finally started including western toilet etiquette to their orientation and even then the problem never went away. Many thought it was completely unsanitary to sit on the toilet and refused to do it.
I recall at my former job in a 10 floor highrise. I had to go to the restroom. So I swing open one of the stall doors only to find UGH...excrement not inside the bowl but on the porcelain seat. It was so disgusting. I’m like “who is stupid to not know you are suppose defecate inside the bowl”. I’m not sure, either the female just squatted on top or defecated standing up.