What i encountered @ sydney totally diff from sydney. In perth, officers stationed b4 immigration and even b4 custom and randomly asking visitors on those food items & etc. in sydney no such officers and once at imi counter they just check what u declared & let u thru thereafter and just b4 the custom, just 1 or 2 officers collecting the yelliw cards and decide which lanes to go. I got 7. Bypassed all screening haha

Simply put it this way, Australians are an honest bunch and they value honesty.
You can pack dry food like biscuits and chips and stuff, no problems.
You just need to DECLARE that's all.
As long as you do that, everything will be fine. And if they deem your dry food to be unfit to pass customs, they will just throw it away.
No legal issues.