And in the old days, the old paper airline tickets were printed on little carbon paper ticket books. As I remember it, the airline would tear out one copy "coup

And in the old days, the old paper airline tickets were printed on little carbon paper ticket books. As I remember it, the airline would tear out one copy "coupon" from the ticket for each segment that you flew before issuing your boarding pass. But paper tickets are pretty much unheard of now days, and I don't think airlines are using much carbon paper. The real reasons they're still around at airports are probably: 1. Compatible with the airline's ancient software and terminals 2. Small size relative to laser printers, can be integrated in to the airline gate/ticket desk "furniture" 3. Highly reliable, and doesn't need expensive consumables. Just need to replace the ink ribbon maybe once a year or so 4. Can print one line at a time if necessary as a sort of ledger/manifest, such as for each passenger who's checked in, and you can tear off whatever's already been printed whenever it's needed