I'll throw my 2 fils in fwiw. Australia does have VERY strict quarantine regulations. As previously pointed out, this is to protect multi-billion dollar industries. Also, the overall general health of the Australian public: consider that Australia actually achieved TOTAL eradication of malaria, when all its near neighbours (NZ excepted) are rife with it. Strict quarantine was one of the things that made this possible. Now consider that, although the ex police poster pointed out that ACS staff are probably Police Service wannabees (and I' m sure there are some in that category), they are, in effect, bureaucratic drones, who come from a system that punishes initiative. Also, on any given day, they are probably at least 25% undermanned so that their Dept Manager will increase his/her bonus. That is the reality of the Aust Public Service today, with managers being on contracts. Overworked/understaffed ring a bell with anyone here...Bueller...
Now an aircrew arrives from an o/s flight. There seems to always be at least one on my flights that just happens to have (you name it) restricted/inadmissable items. I always state before leaving hotel, on bus and then on acft that declare any foodstuffs, what you can bring is limited etc. I have had crew with potatoes for F^$& sake, still try and bring them in.
Combine that, tired crew and an overworked ACS Hitler wannabe and it is a recipe for disaster. They will ALWAYS win, one way or the other. As an Aussie, I find ACS in most of our ports a national embarrassment, but I try and look at the big picture. Do you trust ALL of your crew to do the right thing everytime (even after telling them). My own experience has taught me not too. Aussies are very direct, some people don't like it, but isn't it better to know where you stand? When dealing with any bureaucrat anywhere (Aus, UAE, UK), the best approach is to smile and be a little patient, no matter how much you want to choke them. Also, FWIW, the ABSOLUTE worst customs I have experienced is LAX, followed by LHR. I do agree that SYD/BNE rank up there as BAD!