Cabbies used to routinely discriminate against whomever they felt like, mostly black and brown people who needed to get uptown. That is why the laws prohibiting refusal to take you were you want to go were instated in the first place.
Also, when you say "used to routinely", you are projecting. The press made it into a banner issue, but really, think about it. "Uptown" used to be very, very poor, and poor people don't take cabs.
Is that better? I tried to use shorter sentences.