There are many rules and regulations when it comes to filling the visa application when seeking to visit Australia. This is required for visiting and staying for a specified period. Thus, you need to ensure that everything needs to be filled out properly.
When a visa is issued, the person needs to still go by all rules and exit the country by the time the visa expires. You can also browse to https://www.easymigrate.com/visa-types/tourist-visa-australia/ to get more information about the Australian visa application online.
If someone does stay in Australia longer than the visa allows, there could be trouble for that individual. There have been people that have stayed beyond the allotted time and it is a serious issue. It is not something that will be ignored and there are consequences.
It was a 1996 reform with Australia immigration law that worked to get control of this situation. Often people are deported because they no longer have legal US status. They also can leave voluntarily.
The changes in immigration law were drastic in 1996. Various benefits are denied and some might not be granted another visa or even an extension at this point if they are already on an expired visa.
They could be denied Australia entry for around 10 years in some cases or it could be three years determined by how long they stayed beyond their visa requirements.