I have a completely unrelated question - do the subways ever get "cleaned" ever? I mean taking a power hose to the stations once or twice a year?
The WALLS of the subway system are never cleaned. Every decade they paint over the muck.
And it is not passengers that make the walls of the tunnels black with years of grime. I defy any passengger to jump onto the tracks, climb over the third rail and blacken the far wall!
When could they clean? Why, when any track is shut down for repairs...like once a month at least? So the "4 million people" argument is just a dreary excuse for not cleaning. The real reason is "because they choose NOT to clean."
If every major city in the world can clean its subways, NYC certainly can...if they had the will. They don't.