On a recent trip to San Jose State University (to give a talk to Ben Powell's seminar), I finally figured out what the deal is with airlines putting a "group number" on your ticket. The way I remember the progression, a long time ago ("long time" for my age, of course) they would board first class, then it was a free-for-all.
Then they started boarding by row number. This was a little better; in theory you could board from the back of the plane to the front, to reduce the amount of jostling and waiting. (Inexplicably, though, I seem to recall many flights where they boarded from the front first...)
But now they board by "group number." My first theory was that it was to minimize on people boarding before their row was called, but in retrospect that's pretty dumb. Now I think I figured out what it is: People with window seats (and I think in the back of the plane) are in group 1. Then people in window seats in the middle of the plane are group 2. Then people in aisle seats in the back of the plane are group 3. Etc.
If you think about it, this (or something close to it) is a much better way to get a given number of people into their seats than the two previous techniques. So despite the TSA crap--that reminds me, apparently I'm on their "list" now and the airline has to call them every time I fly!--the airlines are still striving to improve their product. (And don't worry, I'm not a naive worshipper of big business. There was a particular airline that really annoyed me two trips ago, but I'm not sure of their name [my wife knows] so I don't want to smear them now. Needless to say, I will be exercising my consumer sovereignty by not flying them again.)