This is really surprising to me. I certainly have been aware that it's a very long drive to simply take the Thruway all the way to Rochester or Buffalo from NYC, but it would seem that a better way between W NY and NYC would be to simply make use of I-81 and NY-17. Isn't NY-17 at least freeway or expressway grade for the entire journey between I-81 and I-87?
If one is traveling in the Binghampton area, where I-81 and NY-17 split, I-81 south has a control of Scranton and NY-17 has a control of NYC. The signs are definitely guiding people on NY-17.
NY 17 is at least expressway grade, and mostly freeway except for Hale Eddy. The problem is that it's much more winding than I-81/I-380/I-80, has a long 55 mph zone through Delaware County, and ends at I-87 which adds more mileage by taking two sides of a triangle around Harriman.
So, instead of NY 17 reliably being faster, it depends on where you're going in the NYC area. NY 17 is normally faster for Orange, Rockland, Westchester, and southeast CT, while I-81/I-380/I-80 is normally faster for all five boroughs and Long Island (and obviously anywhere in NJ except the far northeast corner along the Rockland county line).
And at least from my quick GSV research, it doesn't seem like there is any good guidance to guide people to NYC once in the Scranton area. At 81/84/6 interchange, the controls are for Carbondale and Mt Pocono. At 84/380 380 only says Mt Pocono. And of course, at 80/380 the choice is Stroudsburg. PA being PA! But at the very least, NYC should somehow be added as a choice in a prominent sign at these three key decision points. In the last two cases, NYC can be a secondary control on the pull through signage, in the first one where there is arguably no room for three control cities, there should at least be supplemental signage for NYC traffic to follow 380 to Mt Pocono.
I agree signage for NYC could be better, but that would be primarily PA's responsibility. As ran4sh noted, NY signs NY 17 for NYC to encourage the in-state route, and it is technically correct that NY 17 to I-87 is the fastest/shortest route to get to the NYC
line (Yonkers/Bronx), but not for anywhere south of the GWB.
The people who don't know that the fastest WNY -> NYC route enters PA, will only have entered PA because of following GPS. Since those drivers are following GPS anyway, I don't see why NYC as a control city is needed for the purpose of guiding those drivers.
The questions at the PA welcome center probably come from people who don't pay much attention to maps/directions, but are conceptually aware of the oddity that they just entered PA while on an in-state trip, so they want to make sure their GPS is accurate.