Originally Posted by
edi_local
How does the airline know you are going to take the return flight if you haven't taken the first one?
They can reasonably assume that, as you've paid for your ticket. If their assumption turns out to be wrong, well they are no worse off as they've still got the money that you paid for your ticket. So in either event, they have lost nothing.
Are they just to assume you have made your way there by other means? Are airlines now expected to just keep empty seats free in the off chance that person who never flew in 3 weeks ago is going to turn up?
See above.