For readers who think this is traumatic, it was, especially in winter nights and your destination is not served by Subway.
In fact, some friends of mine that are Black had to dress extra nicely for an otherwise casual dinner on Friday nights, just so that the cabbies would think (wrongly) that the fare would be for some nice neighborhood. And one had to make sure, he stands on avenues that are not pointing towards Harlem. It was a done thing for a white buddy to hail the cab, and the black friend gets in (There is a certain choreography that goes into this - the black person had to stand close but not-too-close and in a location where he can apparate after the cab has come to a halt but not in a way that gives him a chance to rev up and scoot).
Here is a recent article from Huffpo and Washpo that talks about this in detail:
https://www.washingtonpost.com/posteverything/wp/2015/07/23/...
http://www.huffingtonpost.com/paul-larosa/nyc-cab-drivers-bl...