Fountain of Knowledge

Okay, I've never been to New York, and my city isn't that big, but since we even have street vendors here in Salt Lake I figure I can give you a little info at least.

The ones here aren't open all night, but they will be open until an hour or two after dark, especially in the downtown area, so that's definitely plausible. In the business part of town you probably won't see a crowd that late at night, but just a little further out, where there's more nightlife like bars and such, I'd think you have a good chance of seeing a crowd. Here, the ones near the fast food joints are the busiest at lunch and at night because its cheaper than than the fast food places. There's one corner across the street from a local verson of Taco Bell that always has a street vendor on it and they're always doing good business, even at dusk.

And now that I think about it, on the piers in San Francisco, they're definitely open after dark.

I hope that helps a little bit. From what I've seen here, I bet you could make the scenario plausible without much of a stretch, especially in a bigger city where there's a real nightlife and heavy business foot traffic.