Hi Sharon,
I think the reason is the 'quality of life'. The average Singaporean works very hard throughout his life to pay off the car loan, the mortage, etc. In the process he forgets how to 'enjoy' the finer things in life (not talking about material stuff though). Whereas in Aust, yes you may work hard, but during weekends, you have the opportunity to spend time with your family, do gardening or even the occassional countryside road trip! The pace here is not as hectic (although not as slow as most people thinks). Welfare for senior citizens is also much better...
May I ask which part of Aust did you study at? I live in Melbourne and I find Melburnians to be friendlier than Sydneysiders (heehee). Of my 8 years here, I have never suffered from any form of discrimination. Not even my friends and family. I guess its only when you think you're 2nd class, that the problem starts... this psychological barrier hinders the assimilation into the environment. In fact, I think that the average Singaporean is more racist than Australians. People here are very very nice and friendly! At least when I hold the door the say thank you, and dont treat me like a doorman!
While I do agree that the education system here may not be perfect, but there are its good points. You dont see young children being drowned with homework and attemtping suicide due to the stress. And I think the environment is actually quite conducive for and open to creativity (which is not very common in Spore).
Having said all these... the pasture is ALWAYS greener on the other side! And I do miss Singapore, cause its home afterall! No country is perfect, I reckon its just how your priorities in life fit in with the environment. Somehow I've got a feeling I'm gonna stir up some emotions... heehee... *dodges*