This is actually the view of many. I would have to agree as well. I do not have a lot of time to post a detailed reply today (we are opening a new office this week), but here is a brief synopsis.
Of course one major factor is the cost of doing business in Australia versus Indonesia and the Philippines. Labor is much cheaper, as are materials.
Australia is losing due to a variety of factors. The first is their out-dated quota system. I am not going to get into this because I could probably write a book about it.
Another major factor is Australia's dependence on wild catch in lieu of hatchery-bred oysters. It has always been claimed that hatchery bred Pinctada Maxima will not produce SSP's as large as wild catch, but this is more or less propaganda.
Lastly, many smaller producers are either folding, or being bought by the larger producers. It is widely thought that soon there will only be two SSP producers in Australia. These two are trying to keep the prices high and trying to keep the common perception that SSP’s are extremely rare. I feel that this will change soon with the advent of other large producers in South Asian regions.