I must say that it is nearly always the captain who gives the genuine and full explanation to passengers, which is greatly appreciated.
It seems that often everyone else doesn't really care. I remember once overhearing a Swiss girl checking boarding passes at the gate in Geneva say to her colleague over the walkie-talkie in whispered French: "Oh, just tell them it's a "technical" problem - they won't know", obviously not realising some English people do understand French. Then you get on the aircraft and are told the full truth - we have come from London to rescue you!