My friend tried to use a doctored AirAsia ticket to board in Hong Kong. She wasn't flying AirAsia. They scanned the ticket and found it wasn't a real one. Crafty! But how do they do that? Do airlines all share flight data with each other? Have other people had their tickets checked to that level?

She hopped online and bought a burner ticket and was OK. Just seems odd to me that airlines can check other tickets. If immigration could do it, that makes sense, but airlines?