If an individual can't organise themself to put a couple of sangas and a packet of chips into a bag for the flight, I argue that they probably should not be leaving the country in the first place
However you can't do that!!
Jetstar and Tiger will not let you take food on board the aircraft! Again fine for Syd-Mel but if you were going to Perth no food plus a crap seat might make you reconsider the extra $50 to fly Qantas!