Guess you had never seen some Important points listed below your E-Ticket Copy, Some of them :
$ PNRs having fully waitlisted status will be dropped and the names of the passengers will not appear on the chart.
they are not allowed to board the train. However the names of PARTIALLY waitlisted/confirmed and RAC will appear in the chart.
$...
more... Obtain certificate from the TTE /Conductor in case of (a) PARTIALLY waitlisted e-ticket when LESS NO. OF PASSENGERS travel,(b)A.C.FAILURE, (c)TRAVEL IN LOWER CLASS. This original certificate must be sent to GGM (IT), IRCTC, Internet Ticketing Centre, IRCA Building, State Entry Road, New Delhi-110055 after filing TDR online within prescribed time for claiming refund.
$ In case of Partial confirmed/RAC/Wait listed ticket, TDR should be filed online within prescribed time in case NO PASSENGER is travelling for processing of refund as per Railway refund rules.