http://interactive.nydailynews.com/project/mta-funding/
(the Petroleum tax and State & Local operating assistance combined are less than 10%)
Metropolitan Mass Transportation Operating Assistance Fund: This is a pot of tax money collected for the MTA and other downstate transportation systems. It’s made up of revenue, such as statewide tax on petroleum companies, a sales tax in the 12-county MTA region and corporate franchise taxes and fees both statewide and in the MTA region. MMTOA this year will collect a total of $2.3 billion - 72% of which goes to the MTA.
That fund isn't "purely" statewide.
But the broader point still holds if statewide taxes are contributing all of 20%, the MTA is quite locally funded.
Upstate depends on the MTA region's economic engine for its tax base. Making sure that economy runs smoothly (and that the employees and consumers necessary to that economy can get to and from their jobs and stores) should be a priority for rational, well-informed actors.
I would guess, though, that only a tiny percentage are well informed about what percentage of state taxes come from vs go to various regions. Can't comment on rationality, but with the wrong assumptions, rationality can be counterproductive and irrationality is no better.
NY safe is a great example how far the influence of NYC goes in state government and it wound up getting done despite practically the entire rest of the state being opposed to it.
https://en.wikipedia.org/wiki/File:Green-Star-Map-05-Feb-14....
NYC blaming NY for it's problems is an incredibly out of touch with reality attitude. If something NYC wants isn't getting done at the state level it's probably because NYC's goals do not line up with those of its own elected representation, not because the rest of the state is standing in your way.
The city proper (served by the subway) represents about 20% of the population.
The metro area including parts of Connecticut and NJ (not represented in NY State gov't) is about 20M people. Even if they were all in state, that's still a bit under half the state's total population. And the metro area outside the city proper is still heavily dominated by car culture.
NY State also has several other much smaller but still significant population centers, including Albany, Syracuse, and Buffalo. These areas are not served by the MTA and are also automobile-centric, despite having been founded and initially become boom towns in part due to the Erie Canal (that is, before the railroad dominated shipping and travel, let alone cars).
Some things the city gets its way about, especially when its interests align with those of its suburbs or the smaller urban centers of the state. When it comes to non-car-centric transportation initiatives, however, it generally doesn't.