Australia is a magnificently large continent and country, and the sheer size of the island body gives the continent a wide range of landscapes and levels of elevation. The landscapes span from tropical rainforests to mountain ranges to far reaches of dry, dry desert.
The desert, otherwise known as the outback, makes up the largest portion of the country. If you take the population density of the entire country, it reads quite low; a misleading number, because next to no one lives in the bare stretches of outback that make up the majority of the island. Imagine an island where the edges are lush and green and beautiful, and the whole middle is dry and filled with dangerous creatures and infertile soil. That's Australia.
Now that you understand the basics of Australian geography, you can begin to imagine the culture that might come hand-in-hand with such a strange body of land. People live in clusters of cities, mostly near the water, because those areas have fertile soil, beautiful views, and less of the venomous snakes and spiders and animals that populate the outback. As such, Australia's population is highly urbanized, meaning that many of the people in Australia live in cities, not out in rural towns. The effect of having such a high volume of people living in clustered spaces is a vibrant social life and a level of tolerance or respect for differences that might be less common in less highly populated areas. Australia's citizens are often highly educated, with a reported 99% literacy rate. That means that parents are ensuring that their children attend schools, and that also means that parents tend to live within range of schools. Many countries allow families in especially rural areas to exempt their children from the traditional education required of many urban/suburban families. Because Australia is not a primarily rural country, many students are in range of an education and therefore they are able to pursue higher education fields, giving Australia one of the highest post-graduation education rates in the world.
Many people argue that Australians or "Aussies" are some of the friendliest folks in the world; this concept likely stems from the sociability of the Australian people due to their frequently urban lifestyles. Many Australians partake in recreational activities such as sports, and there exists within the cities a bustling nightlife that allows men and women alike to go out, get drinks, and have fun.
While the friendly culture of Australians may seem unrelated to geography, it is not; imagine two towns. One town has all of the houses a miles apart from one another. The other town is close, with barely a yard in between each porch. When the children in the houses of the first town want to play, they can't go run a mile and get to the others, so they keep to themselves, and maybe play together. The parents probably won't let the kids go off on their own, and so an atmosphere of caution is created. On the other hand, the close-knit community involves interdependence. Children play together, run around unobserved, and maybe transition between households on who gets to supervise them for the day. Thus, connections are established between not only the children, but the adults as well. The first community is cautious and introverted, while the second community is friendly and interwoven. Relationships are easier to build in the close-by homes of the second, and that is how Australia has grown to be so amicable. With such excitement and community at one's doorstep, it is hard to ignore the bustling, friendly culture of Australia.