Service dogs in NYC are allowed to go anywhere a person can go: a school, a restaurant, theaters, sports facilitites, the subway, shops and taxis. As they are trained to help and protect their owners their behavior in all situations is unlike other dogs. They don’t socialize with other animals or with people when they are workimng. They maintian their focus on their owner no matter is happening. See the video, an amazing story of dog heroism when his owner was threatened.
It’s not clear how many service dogs there are in NYC but it definitely runs to thousands. A service dog is trained to help anyone with a disability which might be something obvious like blindness or not so obvious such as someone who sometimes has either an epilectic fit or a PTSD attack. Visitors to NYC fall within all the rules that apply to service dogs here which are generous and supportive of service dogs and their owners, though it would be prudent to carry appropriate paper work if your dog was registered elsewhere.
To be certified a dog has to undergo a rigorous training, see the second video, and is classified as a working animal not a pet. They have special tags and harnesses to allow easy identification. Once all the offcial registration processes have been completed disabled people do not have to explain their disability to anyone such as a restaurant owner. All they have to do is explain their dog is a service dog.
So if you are in NYC and you see a dog sitting quietly beside its owner in an upscale hairdressing salon or walking beside someone in a very busy store you can be sure they are a service dog.