I actually was part of a Science Research Scheme where I got to hang out on a project trying to get plants to do... yeah won't go there.
But the main reasons most people won't go there is
a) even though they say there is money in the field... If you want to stay in Australia... you're pretty much on shaky ground most of the time
b) no security, I met pHders who were working as lab technitions
c) 70% of your funding is not supplied by the government, you have to obtain it from elsewhere. If the company doesn't end up liking your work then they cut your funding. Also if they don't like your results then they will also cut your funding
d) For the above reason, you can't always research what you want, with physics you have to want to do something that companies could jusify funding for, which is not always easy to do, you might end up doing somehting you don't really want, for little money
e) With little pay you can work for years and years and years and still get no major break throughs. Or I actually met a group that came so close to winning the nobel prize, but lost because the English got the break through just slightly beforehand. They'd been working on it for 6 years!
f) Geology in particular was bad, met people who had gone back to CIT to get an IT degree so they could get a job
Australia is pathetic funding wise, its only something like 17% of people who actually stay working in the science field. Its not a lack of graduates, its no funding.