The chances of eating dying from eating pick meat/raw seafood in Australia is almost unheard of. Australia has one of the strictest regulations on food and produce in the world, and it is extremely unlikely that you'll get a parasite. I don't know of anyone who has gotten sick from eating rare (let alone medium-rare) meat, so it's not really something that you should be worried about. You should probably be more worried about going into the sun, since the probability of getting skin cancer in Australia is exponentially higher than getting sick from medium-rare steak.
Also, if it's about health, it's well known that red meats in general are not good for you, and by that logic, you shouldn't eat any red meat. That is especially true for salted meats such as bacon, chorizo, etc. That's not to mention the damaging environmental effects of the meat industry, which is one of the largest contributors to global warming. So if you really wanted to go down that whole not-good-for-you road, then you shouldn't be stopping at medium-rare steak, you'd kinda have to give up any sort of meat.
Being in constant paranoia ain't a great way to live.