re Oracle:
In some ways, you are half right. Because their act of entering Australia without a valid visa is technically an illegal action.
However, due to the fact that the purpose of them entering Australia is to seek asylum. Then, according to the UN refugee's convention, that then they should not be treated as if they are illegal. And furthermore, Australian law also permits unauthorised entry into Australia for the purposes of seeking asylum. Therefore, under current Australia law - their actions are not considered as illegal.
Now, if they enter Australia, and went to mix in the population without a valid visa, and does not apply for asylum. Then, their actions are considered as illegal.
So this is like an exemption.
And it is just like say.... my father took me to hospital with abdominal pain. He illegally parked at a no standing area / or permit zone, and rushed me into the ED. His act of parking is technically illegal, however, his action would not be considered illegal due to exceptional circumstances, and therefore he would not be fined.
Hope this clear things up for you.