Subways and ferries set the pace of motion in New York City. New York wouldn't be the same without its public transportation, and more importantly, the sheer number of people that use that system daily. I know from my own experience, living in San Francisco and Los Angeles, that the Metro can make or break the exploration of a city.
When I went to school in L.A. I significantly used Ubers/Lyfts and my personal chauffeurs (a.k.a. my roommate and other friends with cars). But, the emphasis here is still placed on cars. L.A. always was and remains to be a city built around roads and highways, and cars are still the necessary components of getting around. And, unsurprisingly, cars can be really, really expensive. Either the cost is money (and quite a lot of it) when it comes to ride-shares, or the cost is time -- specifically my friend's.
Public transportation is obviously available and used in Los Angeles, but by a *lot* fewer people and mostly during business rush hours. Afterward, most people aren't seen using public transportation after that evening rush dies down. It's the lack of use, not the condition of the public transportation, that can make people unfamiliar and uneasy about using those systems. Especially, when there are easily accessible, albeit hellish, highways that can be traveled with cars.
San Francisco proves itself to be a bit better when it comes to public transportation, as the CalTrain and BART move commuters from all around the Bay Area. Within the city itself, bus and rail lines (MUNI) also are a source of public transportation. However, there are still quite a lot of people that still prefer cars to public transportation, and that is reflected in the similar decrease in the use of metros past the evening rush traffic.
New York City proves the importance of transportation at all hours, as I saw when I traveled there during the past week. I was able to and comfortable with using the subways and New Jersey PATH trains past midnight and way into the wee hours of the morning. This was significant because of the greater use of these public transportation systems, by everyone. Regardless of background, socioeconomic status, or career path, everyone used the trains and bus systems to get around. They just made sense to.
I particularly enjoyed the fact that I came back to Jersey after traveling around Times Square past midnight and finding myself faced with multiple train cars filled with people at 1:30 a.m. on a Wednesday night. I always felt comfortable and safe due to the sheer number of people around me who use trains on such a regular basis that they didn't seem to think twice about their journey.
It's because of public transportation and the ability to walk across all of New York City that made exploring every street so much more exciting and interesting. I highly recommend that the next time you travel to a major metropolitan city, consider ahead of time what kind of transportation is the most common to get around. It may just help make your trip planning and eventual adventure that much more enjoyable.