You know, there was a BBC article a few weeks ago about new research on who was patient zero for Covid in the UK. The conclusion was that there was no single one, but likely hundreds if not thousands of tiny outbreaks, where only some of those spread far and wide. And they casually mentioned that for example just from Spain alone, each day up until Spain's lockdown 20,000 people filed to the UK.
I've got an 816 page thicc tome on the design of airports that I've read in my bookcase but facts like these are one of the very few ways to properly understand the immense scale of the airline industry. Southwest could still fly half of LA out with that amount of seats.