Shanghai has the largest network in the world. NYC is more compact so it has more stations, sure but that doesn't take away from the fact that Tokyo is the largest city in the planet by population. Shanghai, was a region has nearly 25 million people but the city center is very densely packed. Taipei (Greater Taipei) and Seoul are both 7M and 10M respectively. NYC is about 8M (add another million in terms of tourists and commuters so 9M). Hong Kong 7.4M and far more densely packed than NYC in Kowloon and HKG Island. So as I've stated, population density and ridership is there.

Actually out of the top 10 busiest systems, MTA is 7th in the world. There's no reason for the gross inefficiency, TERRIBLE maintenance, trash, security issues, reliability, etc. No other system I can think of regularly has you ride in an opposite direction, switch trains, catch a bus, and take a shuttle, just to reach a station that was on the original train's route anyways.

The MTA is open 24/7, yes but the ridership is so low that they should be able to use that time to fix the issues they're having. Also systems like HK Metro close for 5 hours at night, run with greater frequency, move similar amounts of people at a lower cost. And HK often comes in as the most expensive city in the world for real estate. So it's not like it's some backwater town with a low cost of living.

The issue is poor governance, corruption, and apologists who try and justify a rotten system.