It's just that a lot of people do biology and you need to beat most of them to get 99+ and that's not very easy. Many people pick biology as their only science subject so they study a lot for the exam and do quite well
The job prospects are higher for USYd students, but even then, they're not great. I know a graduate who is currently working in radiography because he didn't find a full time job. However he's still getting interviews so it's not impossible to get a job either.
holy shit, please don't talk shit if you don't have proper info. Yes, in NSW unis there are no prereq, but many interstate ones do have prereq subjects.