I'm not sure that they're more efficient. Take for example the large open urinals. In a situation dominated by people capable of using them and where most peopl

I'm not sure that they're more efficient. Take for example the large open urinals. In a situation dominated by people capable of using them and where most people are using the toilets to urinate then having Unisex (or Omnisex) toilets is extremely inefficient. A good example of this is pretty much any football (soccer) stadium. For matches most of the crowd are men and a large number of them are drinking more than usual. Heck, I've been in a stadium with a 50/50 crowd: even when the toilets were split 2/1 for women in favor of men there was always a long queue for the girls and nothing for the boys.