In Australia I think there is such a rule, so when they approach the deadline, short of an option: they just cancel the flight. It doesn't count as a delay, and won't affect their statistics of delays!
Some other airlines "swap planes" and do swapsies with every passengers, on every flights, if they get a morning delay; they trickle it down all day long. It's ridiculous seeing lines of people moving to another gate, all day. When your plane arrive at your gate, you know you're being moved to another line and the delayed passengers will get your plane. So that way, delays stay within the bounds!
I'm not sure why the swapsies plan is unreasonable?
I show up for a flight to Mordor scheduled departure at 8 am, you for a scheduled departure at 9:30 am.
The plane scheduled for the 8 am departure is unavailable (for whatever reason) and there's a plane that can board for a 9:30 departure... Shouldn't I get preference since my flight was scheduled to leave earlier? When the other plane becomes available or is replaced, your flight will go out on that (or whatever flight in the swapsies chain).
What alternative would you prefer:
a) Early flight has to wait, maximal delay for those passengers trading off with minimal delay for others
b) Something based on class of booking + airline status + time of booking, like they use for upgrades. Frequent fliers get minimal delay, ultra economy gets maximum delay
c) prefer passengers with connections that haven't yet been missed, otherwise a or b? Maybe just prefer passengers where makable connections avoid an overnight missed connection. This one makes systemic sense, but may not be easy to compute.
If the first plane needs 3 hours to return to service, you delay the first group of passengers by 2 hours and the second group by one hour. There's no need to delay the rest of the day's flights when the plane is fixed.
The person hours of delay is still 2x200 + 1x200 = 600.
Some other airlines "swap planes" and do swapsies with every passengers, on every flights, if they get a morning delay; they trickle it down all day long. It's ridiculous seeing lines of people moving to another gate, all day. When your plane arrive at your gate, you know you're being moved to another line and the delayed passengers will get your plane. So that way, delays stay within the bounds!
Sickening, I'm never flying these airlines again.