they fly with roughly 30 empty seats so that they can take off with reduced thrust and lower flight path. And if a plane that is to fly to John Wayne has mechanical issues, you will have to wait for a replacement that fits their requirements. So your wait can be very long. I have experienced both.

When I was to depart John Wayne, I and 6 other people were denied boarding even though they had over 30 empty seats. I was told I would have to catch a red eye out of LAX but still return to John Wayne. It was my problem to figure out how to get to LAX when I had to leave a car at John Wayne for my return. That didn't go well. Almost got arrested fighting with ticket agents. The return trip had me stranded for hours in DFW because my connection had mechanical problems and they couldn't find a suitable replacement. I and a FAA agent filed nasty complaints with airline.

By the way, the excuses given to me did not fly. As a practicing aerodynamicist, I knew when they were lying.