Do I have to pay half a year's tuition to study in Australia before I can go to coe?

It doesn't have to be like this. Many universities, such as University of Adelaide, University of New South Wales, University of Melbourne, University of Sydney, etc. , you only need to pay a deposit of 10000 Australian dollars to get coe (on the premise of full discount). If the visa is refused, all universities will unconditionally refund all tuition fees (excluding bank fees) as long as they provide a letter of refusal, which is stipulated by Australian laws and regulations, without exception.

Australia is the only country in the world that has adopted national legislation to protect the legitimate rights and interests of international students. Relevant policies can be found in official website, Australian Immigration Bureau. www.immi.gov.au