yes it a complex issue but just because qantas may have been doing it for years does not make it correct. My personal view is if an airline wants to hire foreign crew then they should have a AOC in that country and register their aircraft in that country. It is very poor that the Australian government is supporting a australia airline to outsource their staff overseas. There is no lack of staff within australia that can carry out these duties, so the only reason Jetstar is doing this is to avoid paying australian salaries to staff and avoiding unions.
Singapore maybe ICAO compliant however ICAO rules are only a minimum requirement, so if we only want minimum requirements then fine we can drop our safety stands to that. One of the major differences with Singapore is they have far more lax standards on flight crew duty times. The other fact is Singapore is a very controlled country, so such things as media, works rights (salary and considerations). These controls and non transparency with government, make it a very desirable place for a company to hire its staff.
The fact is Australia companies are trying to compete with Asia, this is just not possible. Unless we start working, longer hours, for very low money...