Yeah, I fly to E3 most years, and always use one of those shared-van services to the airport. Usually it ends up being shared with other people going to E3, so of course we're all hardcore gamers. Guess how many times I've played games or seen other people playing games on the van? Zero. Not once. We generally talk, though we're all strangers.
Once I'm at the airport, and have gone through security, I generally have a couple hours, I might play a game, I might read, I'll generally explore the place and see what shops are around (did you know they now have Best Buy vending machines at the airport selling expensive electronics???) If you're really worried about battery life, they do have USB quick-charge stations at the airport, and sometimes even free power outlets.
Once on the plane of course you can't use any electronic devices during takeoff or landing, and you can't have your Wifi on at all the entire trip, so if you must play as much as possible on the plane, that'll help with the batteries. And some airlines have power outlets too, if you're too cheap to buy a spare $10 battery when you're that much dependent on your gaming system.
When you've landed, most people aren't going to be playing their devices while travelling to their hotel or whatever, they'll be checking out the unfamiliar place while driving through.
I'm betting that the person who came up with the total-game-trip scenario was just making up a scenario that would make the 3DS's battery life look as bad as possible - "look, here's a case where I need better battery life and there's nothing I can do! 3DS sucks, Nintendo should have made it twice as big and heavy so it could fit a better battery!" Sure, bad battery life kinda sucks, and when you do go on that 9 hour plane trip it means you have to be a lot more prepared. But this is a rare situation for most people, and is a common issue for all electronics (which is why they make things called books, vocal cords, in-flight movies, pillows).
