You are being hyperbolic here, but cones around a puddle warrants a discussion.
There have been cases where I have seen portions of a station cordoned off with tape and perhaps with safety cones; however it is not my experience with NYC subway puddles in general. It feels like almost half the stations have leaky ceilings that you can see dripping during rainy weather. No safety cones. During drier days you can find these spots by stalactites and straws forming on the ceiling and by discoloration and mineral deposits on the platform. Two nights ago I noticed something much more frighting on the south bound Prince Street platform. Drip from the ceiling was freezing on the platform and formed an ice-patch a meter in diameter. There were no cones and the subway platform is not the place where I would want to slip. This is a safety issue especially as the whole platform feels only 3 meters wide.
You and I may see MTA workers milling about and appearing lazy to us, but the example of putting safety cones around a puddle doesn't pass the sniff test to me.