think you can still buy the rations in package in beach road
somewhere. Not the same brand one but its for those hikers or
adventurers to bring to eat when along the journey.
I think that combat rations not allowed to take out of camp
primarily because of 2 reasons, and not because of securtiy.
1). If you kenna food poison, cannot say its govt or SAF. so they
dun let you bring out to eat, like due to wrong cooking method or
overly preserved. 
2). People smuggle these foods to sell, so the indents will be more
and more...
