[ghaff]

>Planes don't have the option to just show up and buy a ticket.

Sure they do. Maybe not literally at the door because you have to go through security first. But they'll sell you one at the ticket counter if there are seats available.

[stavros]

Will they really? As far as I know, they stopped doing that years ago, but I might be wrong.

[rtkwe]

They'll still do it but most planes are oversold already to increase utilization, some of the airline's high rewards levels allow you to force your way onto planes too.

[throwaway290]

I've seen people buy tickets at the airport with cash before same day flight this year. I came to the airport and changed my ticket to depart on that day once.