O dear, that sort of thing (lacking passengers) wouldn't be good for the airlines budget or the tourist dollar of the country of destination be it South Korea, Bali or anywhere else.
I caught a Singapore Airlines Flight in Kuala Lumpur in 1982 for London (my dad had just passed away) It was November 1st. It was as full as those pictures. Three of us in the area I was in, and all the other areas of the plane just as sparse. The cabin staff kept sitting with us and yarning for ages during the flight as they had nothing to do.
Once I had mentioned to one of them of my dads death I could not keep them away. A very good looking Singapore Airlines Girl said I will bring you a brandy? A Brandy Glass from 1st class I presume was brought and filled up with very nice brandy. Also at each meal wine followed by coffee and the Large Brandy Balloon. I had never drank much brandy at that time, hence I was pretty hung over when I got to Liverpool. Telling my mother and the family how bad the Jet Lag was.
Never had a brandy as good as that stuff on the empty Singapore Airlines Flight .
I wish they had put me in First Class and gladly given the Brandy a miss.
I was on the Korean Airlines flight from Seoul to Honk Kong 12 months to the day that the Russians shot it down. en.m.wikipedia.org/wiki/Korean_Air_Lines_Flight_007
Only self, missus, 18 month son and 3 1/2 yr daughter upstairs with two Japanese business men. Hardly anyone down stairs. It was 10am. The drinks trolley, soft and hard, was put in the middle of the aisle. It was self serve as the hostesses had taken my two blond haired, blue eyed kids to the galley for pictures, games and flash kids food. The two Japs and self emptied the grog trolley. We had the wobbly boots on trying to negotiate the spiral staircase. Fun trip.