@natematias asks "Why can't someone design public loos that don't result in 40 women queueing?" (via @j4ngis).
There are of course two different questions here - not just the challenge (designing a more convenient convenience) but the frustration ("why can't someone DO something?").
There are many annoying design problems that are never solved, not because they are technically difficult but because they are organizationally difficult. Lots of stakeholders who are sometimes inconvenienced, but nobody cares enough about the problem to do anything serious about it.
One of the expectations we have of architects is that they should anticipate as many of these problems as possible, and design systems and spaces that don't unnecessarily inconvenience the user. Unfortunately, many architects are more interested in grand sweeping designs than in paying attention to small details. (And in the built environment, architects often seem to lose interest in a building once it's been constructed; fixing any design problems is someone else's job and comes out of the maintenance budget.) When I travelled through Heathrow Terminal Five for the first time, I was shocked to discover that the toilets were at the end of a long corridor, as if they were added as an afterthought. (You might expect that kind of thing after a building has been modified a few times, but not in a brand new building.) Obviously the convenience of passengers ranked far lower than the commercial interests of the retail units.
Coming back to the toilets at St Pancras Station, which was Nathan's starting point. There are toilets on the platform, there are toilets on the trains, and there are toilets in nearby pubs; all these vary by convenience, cleanliness and price. But whose responsibility is it to provide adequate toilet facilities to passengers? The obvious answer is - those who sell the liquid refreshment should provide the outlet. In other words, the pubs outside the station, and the countless coffee stalls inside.
Nathan presents the problem in terms of an unwanted outcome - forty women in a line. (And I'm imagining at least forty men waiting for the forty women - obviously not one each but unevenly distributed - a husband and two sons here, a boyfriend over there, a chauffeur and a few press photographers near the exit, Nathan himself pacing up and down. Not even talking to each other, but glancing at their watches twice a minute.)
There are many ways of eliminating an unwanted outcome. For example, someone could build more loos, or install mirrors alongside the queue. Someone could erect a separate urinal for the men, and then make all the existing loos unisex. They could ban coffee from the station platforms, so people wouldn't need the toilet so often.
But who is "someone"? Who is "they"? That's the real design problem here.