[thaumasiotes]

You have difficulties showing up to your flight three hours early because checkin is not available that far in advance. But the airport obviously is open that far in advance. Planes are departing and landing at that time. The checkin counter may be open (or may not; volume does go down).

It it likely true that "most airports" are not operating 24/7, but how is that relevant? It could be just as true that "most airports" don't serve commercial flights at all. The airports that have a lot of passengers are operating 24/7. We're talking about a metric assessed per passenger.

[AlotOfReading]

I'm not talking about the check-in counter, I'm talking about general security that non-charter passengers always have to go through to board a flight. Security checkpoints operate limited hours at even the largest airports, like LAX where they're open from 4h00-22h00 max. If we look the departures for LAX today, we can see that no passenger planes departed between 2h00-5h00, except for one charter jet out of the private terminal. Yesterday had no such departures, only the usual nighttime cargo flights.