Originally Posted by
notquiteaff
I never understood how possession of a boarding pass or a screenshot of one proves that someone was actually on a particular flight. (And yet I know that airlines at least in the past have asked for it; not sure if they still do in the age of apps and smart watches)
They've been known to ask for used BPs. That's why I always print one, at the airport kiosk if I can - and this from a recycler and treehugger.