Is it possible to walk across the Australian continent East to West (or W to E)? In other words, as an American, only familiar with movies/tv shows, etc, I think of Australia as a wasteland in the center. Would it be possible to backpack(hike) across as a (personal) achievement?
Now that you've clarified in the comments, yes, it's entirely 'possible', but not easy, by any means. As mentioned by @Relaxed, only 37 people have been recorded successfully completing this challenge.
As an American, you'd be the 5th American citizen to complete it, if you did it now.
Some (crazy) people have even run across Australia.
One of the stories I've heard is of a guy who tried to walk from the South to the North, and he failed 3 times - due to too much water! Crazy to think of, but the cart he was pulling behind kept getting bogged down in mud north of Adelaide.
However, as you note, much of Australia is desert and pretty inhospitable, with >85% of the population living within 50km of the coast (Sorry, old stat, but if anything that's probably increased).
People have died when their cars have broken down, because of the lack of cellphone reception and almost no other traffic.
Friends drove from Sydney to Broken Hill a few weekends ago. They sometimes went 3 hours without seeing another vehicle, and there were big signs warning when there was a slight bend in the road, as so many people just zone out on the long straight roads.
So yeah, it's possible, it's an amazing achievement that very few people have been recorded as having completed, but it would not be easy by any means.
Bonus fact: Of the people who have walked around Australia, it's taken them 365–401 days to complete the walk.