This is such a lovely parable! Still, I wonder what Dijkstra meant with the sentence
> true mathematicians, however, fail to see the point.
I would have expected mathematicians to appreciate the nice symmetry of the proposed solution and am curious about the other point of view.
Presumably true mathematicians operate exclusively in the realm of theory and can't understand (the point of) practical implementations, which programmers tend to enjoy when the solution is elegant.
I was sure that they’d return to a toilet in every car by the end, and the moral of the story would be about optimizing for the wrong thing.
Can the turntables hold two cars at a time?
There is no need to turn the set of two cars -- it always has a toilet in the center so it's symmetrical.
Easy problem to solve. Put all the toilet cars up front, charge 3x for those seats, and say everyone else is "complaining about a lords and peasants sort of thing."