I also agree with Keg with regard to PA's from the flight deck. I have NEVER been on a flight where the captain or other flight crew have lied about the reason for a delay.
Arrived in Syd late, too many hold items, too much OSIP. Tried loading pax to assist with dispensation approval - still had way too much work outstanding. Pax would have to be "entertained" on board for a long time. QE management willing to bend the rules to breaking point in an attempt to get it away.
So, on this occasion the pax would have been greeted by a PA by from the flightdeck "welcome aboard, we've got no prospect of actually departing cos the plane is so broken, but we thought we'd board you anyway to try to sham CASA into letting us break the curfew, and give you some illusion of movement. Settle back, enjoy the view of the tarmac, you'll be looking at it for a while, and enjoy the famous qantas on ground service"?