Often commenter Ian Argent has an interesting post on how our society treats children:
I certainly wasn’t an adult at 12-13. But I certainly wasn’t helpless, defenseless, or hapless. I no longer needed the kind of close supervision a young child might need – I was allowed to operate within fairly loose guidelines (in some ways, looser guidelines than I was when I was in my later teens, because I did have somewhat less responsibility). Nonetheless, I’m quite sure that had the need arisen for me to fly unaccompanied, my parents would have made sure the people at the other end knew my flight info, and then dropped me off at the airport (accompanying me to the gate if possible under time constraints), and expected me to make my way onto the plane, into my seats, and off the other end to the people I was going to without expecting much, if any, official support form the airline.
I flew to see my grandparents in Florida when I was pretty young, in so far as I can recall, I was in this age group. It had to have been a while ago, because Eastern Airlines ceased flying in 1991. You have to wonder about an airline who’s logo is a seatbelt. What’s that supposed to mean?  “Hang on, it’s going to be a bumpy ride!” or maybe “Eastern, wear your seatbelt or you’ll die.”
I seem to recall the grandparents dropping me off at the gate, and my parents picking me up. Of course, now you can’t do that because we’re all more worried about terrorists than perverts or kidnappers, but that was also in the days before cell phones, when all had to be pre-arranged, and it was just hoped everything would go off without a hitch. Nonetheless, Ian has a good point that kids today are no doubt not any less safe than they were twenty years ago. That’s certainly true, even with all the terrorists.
I flew lots of times as an unaccompanied minor. My grandmother would purchase the extra service for me up until I was too old. I didn’t mind because the stewardesses weren’t stupid, they could tell I was a relatively independent person and could generally take care of myself.
However, it does offer perks: You get to board even before pre-board people. You get a ride through the airport if your connecting flight is really far away. When you hit the call button for another glass of water on an 8-hour flight, you get faster service than everyone else. :)
That said, I do think it’s silly that the article in question acts like you’re done for when you hit 12 on Southwest. I flew alone on Southwest when I was about that age and while I didn’t have supervision, it’s not the like the flight staff didn’t notice I was flying alone. They just checked in on me a little more often, asking things like if I knew where my brother was going to be picking me up at the airport, if I knew my way to baggage claim, etc.
I used to fly alone when a small lad, but alas, I grew up and the magic was gone. My arms were tired anyway.
My wife and son had to fly out after she had a very bad sprain of her foot (she had to be wheelchaired to the gate), so I asked TSA and the Airline for a escort ticket to watch over my 2 yr old while they were escorting her in the chair. I got the escort pass and was allowed to hang out at the gate until they were boarding. You are still allowed to escort someone to the gate, but it is up to the Airlines and TSA if you are given the pass.
Of course, I had been flying internationally (under supervision of parents, admittedly) since I was 2 yoa…
My bigger point was this is another example of the infantilization of the preteen/young adult (IIRC Young Adult fiction is specifically aimed at 12-16 YO readers).