The ware would most likely come from someone that has a spare battery that is ready to go. Think of your phone burning 80% of the juice and you’re about to hop on a flight that you’re barely going to make (no time to charge). Slap that stand by battery in and off you go. That’s what I did with my old Nokia or blackberry back in the day. Oh and for my HTC aria.
True there are places to charge on a plane or bus. My example is just what I could come with in terms of just needing instant juice. I like having the option to have power for my phone. Multiple ways to skin a cat. :)