Apparently, nobody’s watching the watchmen. Private security guards hired by the Metropolitan Transportation Authority to staff subway stations, and act as deterrents to would-be turnstile hoppers, have instead been lending a helping hand to the Big Apple fare-beaters. The Post recently observed Allied Universal Security Services guards inside the Herald Square station holding the emergency doors open on two different occasions to let a stream of scofflaws through. ... Several commuters could be seen walking up to the gate, and exchanging words with the guard, who then let them in. Whenever the guard opened the door, other fare-evaders would make...