Let's make sure we understand Winston's argument. Winston argues that for the PTA to operate without a budget deficit, it must (necessary condition) get rid of its late-night services. Winston's reason for this is that the fares collected in these late-night periods are "less than the cost of providing the service". In other words, the service loses money in these periods. Winston then anticipates a counter-argument: why not just raise the late-night fares? Because fare increases need to be authorized, which would take two years.

So far, Winston's argument makes sense: if late-night services lose money for the PTA, it makes sense to cut those services and reduce the deficit. But Ping responds with a counterintuitive claim: actually, cutting the late-night services would lose more money from lost fares than it would save on operating costs. The reason for this is that there are riders who leave home in the daytime and then return at night. Losing these riders, in other words, would actually mean losing two fares, one daytime fare and one nighttime fare.