The roads are mostly resurfaced on a schedule that has them resurfacing nearly every day of the year. There is just so much more abuse on Manhattan asphalt from large trucks, heavy trucks, cars, construction, etc. that any given individual point can appear run-down, but then look fresh and new as soon as it is cycled through. You don't see many 16m trucks abusing streets in Rome :)
Resurfacing every day of the year is kind of a meaningless metric, though. If the entire resurfacing department is 1 dude, he can be resurfacing every day of the year and only get a (couple?) streets done. The argument there is that the department isn't large enough, which fundamentally impacts the availability of good roads.
Trucks are another thing entirely, and I'd be delighted for them to be both taxed at a higher rate for road wear & tear, and to be somehow limited. But that's road design, and that's not going to be solved for a long time.
Re: Truck taxing, it doesn't have to be a long time -- we just have to not elect idiots. Bloomberg pushed it in 2008, NYC Council voted for it and the NY State Assembly shot it down.
> There is just so much more abuse on Manhattan asphalt from large trucks, heavy trucks, cars
"Abuse" is the right word. Perhaps it's worth rethinking how much of this abuse we allow. Giant trucks parading through Manhattan at will, tearing up the pavement, endangering cyclists and pedestrians, and generally lowering quality of life for residents is a policy choice, not some natural and unchangeable fact about the world.
I'd actually just settle for enforcement of existing law. 53' trucks are illegal in NYC, as is driving a truck down a street that is not a truck route. The NYPD could generate a lot of income if they simply enforce the laws on the books. You constantly see 53' trucks driving around (they even literally say "53'" on the side) and no one cares... until they make a turn and get stuck and block up traffic for a mile.
You don't see many trucks abusing the streets of Rome, only in certain areas. That said, I generally actually find the pavement in Manhattan better than in Rome.
http://www.nyc.gov/html/dot/html/motorist/resurfintro.shtml