That's a little unfair, you've probably only ever tasted Fosters, a beer which is not even sold in Australia (except as a novelty).  I've spent several years in the UK, and I will say that the median beer in both countries is about the same.  I've also lived in the US for a few years, and the beer there isn't too bad either.  The problem is that the foreign exposure tends to be the mass produced, pasteurised stuff that is completely forgettable.  For example, given a choice between the 6 varieties of stout at my local, Guinness ranks bottom.  But the Guinness I had in Dublin was quite a different beast to anything you can get in a can.

What is frustrating is the lack of microbreweries in Australia, they were all bought up by Lion Nathan in the 80s and closed, leaving only a small number of brands on the market.  Thankfully the tide has turned and small breweries are opening up everywhere.  It will be many years before we return to the 'pub on every corner' situation though.

http://en.wikipedia.org/wiki/Beer_in_Australia