Im not sure why Staten Island Railway's on there, that would be the equivalent of the 174km long Overground system in London (mass transit, rapid train that has a start terminus and an end terminus in the city proper -it often shares tube stations and parts of it were once the tube, but renamed). The O is extensively used as it allows passengers cross-city transport without having to enter the centre each time, unlike the radial tube network. 625,000 people ride it each day.
PATH would be the equivalent of a few other lines in London, such as the Elizabeth one (118km, a whopping 800,000 users daily). It was initially planned as a new tube line, before they rebranded it as a standalone midway through construction.
or the 225km Thameslink (850,000 users daily)
These mass transit systems within the city (not mentioned, but if you include the DLR too - London's light rail network), would put London at 945 km alone, overtaking Beijing and Shanghai. That doesn't include any mainline trains that bypass or terminate at any of the 14 major rail termini, who have hundreds more stations and tracks (within the city, used mass transit-wise).
But yeah, I wish they'd consolidate it all, or at least have a list of consolidated systems. Paris, Seoul and Tokyo notably miss out too.
I think Beijing has less metro rides per resident as there are so many options for transport there - a bike ride for hours is just 80c, and they're everywhere. Once you take the metro to a near enough stop, you likely switch to electric bike. Having spent some time in China recently, the metro networks are indeed far ranging, have great coverage, are frequent, safe, clean, all mod cons -you can even choose which carriage beforehand by checking how crowded it is or the live temperature of the aircon (cooler in the middle, less so at either end), before the train even approaches.
However it's not total plain sailing with long times to even get to the platform as theyre so deep, with long transfers (some took 30 mins with crowds), and often multiple times -by comparison for Central London you only ever need to transfer once, at most twice. It was often frustrating depending on the city's layout -Chongqing I'm talking to you. Although never as crowded, frequencies weren't too hot either -about 7 mins between trains when I'm used to 2-4 a lot of the time. In London we rely on the highest frequencies in the world to manage the crowds, as the tunnels are old and smaller, forcing the trains into bullet sizes (hence the nickname of the Tube). If a rush hour train is delayed by 1 or 2 mins it can mean the crowd doubling and trying to get on. Sounds lovely and convenient on paper but it's often disastrous.
However the bikes in China are an absolute gamechanger, SO easy to find (millions of them everywhere, different companies, even in random rural-like areas), to use (scan the barcode to unlock), and incredibly cheap -pretty much free. You can use the bike lanes or the traffic any which way you want. I'd often use them instead of a second metro ride.