So I'll ask the obvious question as a person who has visited, but never lived in, NYC. Why is this a problem?
I've never had a problem getting a cab to take me where I want to go in the cities I've lived in nor the ones I've visited. The only downside I can see is if you're requesting somewhere that's remote and that would be difficult for the cab to find another fare on the return trip. NYC does not strike me as a place that would have this problem.