That is quite true however it is not as easy as implied. Why do you think you won't be able to get in after high school? what do you think will be holding you back?Why do you think you wont get in straight away?
You only need 93 ATAR + a decent UMAT.
Although you may really want to get into medicine, I would strongly advise against doing a degree that you see as a "pathway" into medicine. If you do not particularly enjoy studying this and hence your sole reason would be "to get into medicine" you are short changing yourself. Just imagine the amount of people who are thinking the exact same as you. The competition will be high and the stakes are weighed negatively in your favor.
My back-up, which I accepted before I got a late-round offer, was Physiotherapy at USYD. I chose physio because I actually enjoyed learning about how the muscles and the physiology of the body work. So please do yourself a favor and choose a back up that you would enjoy doing.