Perhaps all of you are simply more likely to notice or remember when it's someone of a different background and forget when it's someone of similiar background. As a male, I think all men are slobs in public restrooms because it's not their own place. I notice urine sprinkles on the toilet after women of various races leave the stall. Many women prefer to hover rather than sit on a public toilet or take the time to spread paper on the seat. Asians were taught that bathrooms, especially toilets, were unsanitary, and therefore, Asian women tend to squat when they urinate.
Squatting causes the urine to spatter onto the toilet seats.
Rather, I think it happens because women are taught as young children not to sit on public toilet seats, but rather to squat over them to avoid germs. The problem lies in the fact that no one bothers to wipe their splatter from the seat when they're done, thus leaving it for the next person, and the person after that, and the person after that. Take a wad of toilet paper and wipe the seat clean.