Originally Posted by
secondsoprano
Why do airlines require you to check in?
It can't be to see that you've arrived at the airport ... because you can do it online when you haven't left home.
It can't be to make sure you're really intending to fly ... because you can do it right at the gate at the last minute.
It can't be so that they know what seat you're in ... because they will allocate that anyway.
It can't be to confirm allocation for upgrades etc ... because they already know who is flying.
So what does "check-in" even mean these days?
For one, TSA isn't going to let you anywhere near the gate without a boarding pass (or gate pass in some airports). Not everyone can to online check-in.
Another, bags. Can't drag all your bags to the gate and check them in there.
Another, you make an assumption that the airline knows who is flying. Check all the threads about "overbooking". The reason that they overbook is that a percentage of passengers don't show up for their flights.
Another. Load and weight distribution. Particularly for small planes. If people don't show up for their flight then the airline can load more cargo.