It does kind of suck though that one day she is free and the next she would cost a couple hundred dollars.
It's not that one day she 'is free' and the next day she's not; it's that airlines allow children under two to fly free in the parents' lap, despite it not being particularly safe in the case of turbulence or even a rough takeoff/landing. The FAA permits it because it flying is safer than driving - but pretty much everyone discourages not buying a seat for even a small child.
As for the age cut not being fair? One day you're not old enough to drive; you wake up the next day and despite no change in judgment, maturiti, experience, poof! You are old enough to drive. Same with getting married, entering into any contract, even drinking - at 20 years and 364 days, you can't legally imbibe alcohol; enter a bar after midnight on that same evening, when OBVIOUSLY nothing's changed in you, and voila! Magically, the law allows you to drink.
I totally understand everything you all are saying too and a seprate seat does sound nicer as well. My DH is just so cheap, he will think of it as a waste.
Oh, really? Is
he going to keep her in
his lap for three hours straight? Have him practice at home. Now, granted you probably don't have a chair in your house that's as limited in size as an airplane seat, but if you've got a dining chair with arms, or some other small seat, plop your daughter in his lap and see how long they last like that.
Now isn't this interesting: We have flown with my DS3 at least, say, 15 times. Round trip. All cross country flights, most with layovers. Sometimes we purchased him a seat (when he was under 2) and sometimes we didn't. We have NEVER ONCE been asked to provide proof of age for him. We quit bringing it because nobody ever asked for it. We fly mainly United, Delta, and Continental.
Better to have it and not need it than... anybody watch that show "Airline" on A & E? It's been cancelled, but one of the incidents they aired was a family with a child of questionable age, and they didn't have the birth certificate. NONE of the options the parents were given included Southwest just overlooking it. They ended up getting a copy of the birth certificate faxed to the airport by someone back home.