Random semi-off-topic. Why do we, in this day and age, still need to keep boarding passes to prove we are on a flight? Surely the most accurate information is actually with BA/Qatar/the airline?
I could checkin online, save the boarding pass and not go anywhere near the airport. I'd try and they'd claim I wasn't on the flight. But having a BP is somehow "proof" if something goes wrong?

I do keep all my BPs for this reason, but I'm just curious why we still need to.