Road maintenance and expansion is not really the point. It's not like midtown has a bunch of extra room to build new roads. It's more of an admission that eventually you're just gonna bump into hard physical constraints that no amount of money in the world is gonna help you get past.
or that the taxes are far too low to support the cost of road maintainance
Doubtful - we're talking about New York, after all.
New York's problem is that its fuel consumption has been flat for 50 years because of increasing fuel efficiency and low population growth. Meanwhile, everything else is more expensive to maintain so it must make up the difference with other funding sources or higher taxes. The latter is is difficult political issue when they are already near the top for state fuel taxation.
I don't think fuel taxes are enough to pay for road maintenance anywhere in the US. It's always supplemented by some amount of general fund dollars.
Following up on my own post: as usual, anything that goes against the HN hive mind gets down voted.