Poor doors: the segregation of London's inner-city flat dwellers | Society | The Guardian:
"A Guardian investigation has discovered a growing trend in the capital's upmarket apartment blocks – which are required to include affordable homes in order to win planning permission – for the poorer residents to be forced to use alternative access, a phenomenon being dubbed "poor doors". Even bicycle storage spaces, rubbish disposal facilities and postal deliveries are being separated."
Thanks to Mystery Reader for another example of the rich separating themselves from the hoi polloi while enjoying the planning benefits that are supposed to go with mixed income developments. The same thing is happening in New York.