it is working only because it is GR and low cost ticket ..run an AC express and definitely u will start finding vacancies in current reservation most days of week..Indian middle class mentality is first money then luxury ..so they see the cost of the ticket first and then after tht they see the luxury ..best example that i can site is of NZM - MAS GR ..the worst GR as far as maintenance is concerned ..filthy coaches ...broken AC doors ...improper cooling ..but still runs full always..