As a former HR officer where I had to do the hirings and firings I totally empathise with you. To answer your question bluntly this practice does happen, not neccesarily by intent and I dont think its restricted just to Australia.
Basically employment terms dont begin until a contract is signed. Even then its not permanent until the employer has it in writing. And yes you are right in treating this as a learning process, that you need to really spread your eggs in every available basket because its a real dog eat dog world of securing employment here regardless of which state you are in. Dont take this as a negative, its just that someone more qualified perhaps got the job ahead of your husband. I wish you all the best in your future endeavors. Things happen for a reason, theres probably a better and more transparent employer round the corner willing to take on your husband. Best of luck.