G'day Andy,
Some Aussies do eat some of the pigs they shoot, but are very selective in doing so, being more inclined to eat younger ones.
But most of the time, Aussies - even the ones who do eat pigs they shoot - will just leave them to be eaten by the native wildlife (or other pigs).
Caution must be exercised when checking a pig for its culinary suitability over here, but this isn't too difficult.
The difference between hunting in Australia and hunting in the USA is that we are basically attempting to either eradicate or limit the growth of feral species only, whereas you guys are managing native animal populations. As such, we don't have the same recovery laws - also, sometimes the environment and climate we're in makes recovery difficult or impossible.
The Aussie deer hunters treat deer very differently, with it being utilised fully even though they are feral too (they do live in more temperate parts of the continent).
Here's a link to my camel thread where I wrote a little more on this topic:
http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=040728 Cheers,
Ben