To be fair, the NYC subway can be extra confusing for tourists from cities with more "predictable" metro systems. For example, in the Madrid and Barcelona Metro

To be fair, the NYC subway can be extra confusing for tourists from cities with more "predictable" metro systems. For example, in the Madrid and Barcelona Metros, all trains departing from each given platform are guaranteed to belong to the same line and will serve the same stations from A to B—no need to think at all. That's also usually the case in the London Underground, though some lines may split and there are some exchange stations where you need to pay attention as to what line the train arriving at the platform belongs to. Now compare that to the NYC Subway, with its routes, lines, express services, local services, etc. Anyone used to the simplicity of Madrid or Barcelona style systems is bound to find it confusing. Not that I have anything against the idea though, it's just a different philosophy and it is connected somewhat to the NYC Subway's rare 24/7 service. I have fun memories of when I went to New York with my parents when I was 18, and they were simply unable to understand the Subway in depth and relied on me to make sense of it.