To be fair, in NYC it is not out of the realm of possibility that the car hasn’t been moved because there’s a dead body inside.
But usually, the cars are towed long before a “slew” occurs
I live in NYC, and I agree with you. We're continually reminded, “If you see something, say something”, and “something” means even things that are mildly out of the ordinary, as you don't know what could be behind it. I once called 311 — the much lower-key version of 911 — to report a small, full overnight bag that had been been abandoned on a street corner on the Upper East Side. The 311 operator told me, “That's no small thing; I'm putting you directly through to 911.”
So, Hanks did the right thing. You just never know.