Delta Air Lines flies empty planes just so they can advertise that they never cancel flights. It comes from this site where Delta pilots are bragging about it: https://www.airlinepilotforums.com/delta/122028-no-cancellations.html
Two examples from the site:
On 05-25-2019 ‘DARR31’ wrote: I know a captain that got called for a green slip to fly a jet from SEA to PDX and back empty both ways. I asked him why and he said that they needed to show completion for the flight number. That is how they get away with saying no cancellations!
One minute later ‘notEnuf’ added: Flew an empty airplane just to pick up flight attendants to make it a revenue flight. I think they said 48hrs after originally scheduled. The station didn’t bother cleaning the plane or catering or dumping the lav. Apparently the FAs needed to be on board for it to operate as a revenue flight. No pax, they had all been accommodated over a day prior.
High school student worried about my future. I was shocked that Delta flies empty planes just so they can claim they never cancel.