One of our family friends couldn't afford to go straight to uni and couldn't get YA.... she got an early offer in to the course she wanted to do and you couldn't defer it. She had no choice but not to go.... then the next year she couldn't get in. Hence, she was crushed and all her hard work in yr 12 didn't pay off.
Plus it can be extremely hard to earn that $16000 when you are in a place where youth unemployment is high. In Alb it is very hard to find full time work or even a job as a casual where you get a decent number of hours a week at 18-20 yrs of age. A lot of people I know deferred and then still couldn't earn the money due to being stuffed around by employers and being unable to find a stable job. In Alb there is also a trend where the fast food restaurants and supermarkets start to cut back your hours drastically when you hit 18... they then give your hours to a 14 yr old.
I think that YA should be assessed on individual cases. I don't think that the clear cut earnings thresholds and assets/parents earnings stuff is a good enough assessment of a person's true need for the allowance, and they should be able to make exceptions if you are a bit under the earnings and have a good reason for needing it (like moving away to study) or in the case of the girl who couldn't defer her course etc.
But, I guess bureacracy works by slotting people in to holes, using numbers etc instead of examining people's actual situations.