And here is another scenario, using a slightly more complex spreadsheet. This allows for 2% income growth.
Labour say a $15,000 loan balance and annual salary of $27,000 growing by 2% per annum will take 40 years to repay.
The attached spreadsheet has it repaid in the 24th year. And once again note this is not even allowing for interest writeoffs. As half of all payments (after inflation is accounted for) go towards principal repayment, there would be interest writeoffs for the first half dozen or more years, but to keep it simple I am ignoring those.