I'm fortunate that I can easily fall asleep on planes, but unfortunately this also means that I'm usually asleep when the flight attendants come around to hand out immigration cards. Given this is meant to make the customs process more efficient, it seems like airports should want to ensure that everyone has the necessary forms before they exit the gangway. But, because many airports have staff directing passengers to the necessary forms as they get in line to go through customs, most airlines seem to do this more as courtesy to airports than anything else.
With plenty of time to fill out the immigration cards while waiting in line, it's unclear why they're distributed on board in the first place? This process adds minimal efficiency, while causing stress for passengers who later realize they never received them or forgot them.