hostile architecture

There are no seats in the main hall, where people wait for trains.

Over the years, the MTA has been accused by homeless advocates and urban planners of deploying increasingly uncomfortable seating arrangements as a form of "hostile architecture."

The origin of the green chairs can be traced back to one urban planner's observation that 'New York is a tough town to sit in.'

'There are these battles of access that often play out through architecture and urban design. They seem neutral at first, but then they become political.'

Why did Frederick Law Olmsted and Calvert Vaux decide upon this frustrating design feature?