We have a government-run loan scheme called HECS. You defer your university fees throughout the duration of your studies, apparently no matter how long they last. The programme is not means tested at all, so it is available for every single domestic student studying uni here, no matter what.
That loan is then paid back only once you start earning more than a threshold amount of taxable income (this year, $51,309 - it's not a low income by any stretch) and the payment amount is graduated depending on how much over you earn, from 4% of your income at that threshold amount to 9% once you hit $95,288 or above [1]. There is no real interest charged on the debt - the loan is only indexed to CPI every year, so that the real cost of the loan amount doesn't change. The repayment is treated like tax - either taken out as you earn your wage or squared every year upon doing your tax return.
The perk that rich people get is that if they pay their bill upfront (that is, each semester as they study), they get a 10% discount on the total cost of the tuition for that semester (apparently, off memory it was 25% when I went through about 5-10 years ago). If you put it on HECS, you instead pay the full amount.
Oh, and also for every domestic student, a semester of full-time study costs on the order of $3000-$5000, so a 3 year degree is about $18k-$30k of the above debt [2], depending on what you study. It's heavily subsidised by the government.
The system is funded, in part, by international students, who pay the full fee amounts (no government subsidy) if they choose to study here.
The major criticism of the system is that students can just incur this debt then flee the country. If they earn no taxable income here, they never have to pay it back no matter how much they earn overseas. I can't really think of an easy way to resolve this because it's impossible to garnish income from another country. Nevertheless, the system works reasonably well.
[1]: http://studyassist.gov.au/sites/studyassist/payingbackmyloan...
[2]: http://studyassist.gov.au/sites/studyassist/helppayingmyfees...