Not 100% true (Look it up on the NSW birth,deaths and marriges website)
Depends on which state in Aus you are in.
If you live in NSW, and you get married in Thailand, it will be 100% legit in Thailand ONLY. As NSW does not recognise any other marriges from any other country whatsoever, unless a specific procedure is carred out)
If you are planning to get married in Thailand and you want it to be legit in Australia you need to...
Submit application in NSW at least 1 month and one day in advance eg. papers stating...I such and such wish to marry on such and such date. Plus other papers stating that both parties are single (not currently married etc)
Once that is done you need to wait for the official papers from the births, deaths and marriges office.
Once you have those papers, you then (both parties) need to go to the Australian Embassy in Bangkok and have the papers stamped.
Only then will it be recognised in aus.
If you can't do that, I suggest you just have a wedding ceremony in Thailand (unofficial) and when you get back to Aus, you can then do the above paperwork and head down to the marridge registry and have a quick ceremony, which can cost as little as $100AU
Check it out here......
http://www.bdm.nsw.gov.au/marriages/...sMarriages.htm