That's an interesting thought- I've primarily talked to people living in the US midwest who dealt with bathrooms used primarily by lower to middle class individuals. Perhaps more upscale locations force a higher standard?

The assumption I've always been given is that women are more prone to hovering (germs!) along with the obvious biological differences that allow for more..erm...variety in terms of mess making. Seemed a sensible enough explanation to me, but it's very possible that there's more to it.