Which websites do people use in Australia for the purpose of chosing local restaurants?
As of 2019, Zomato (formerly Urbanspoon) https://www.zomato.com is the most popular Australian review site by a mile. It covers everything from kebab joints to frou-frou five stars.
The Good Food Guide https://www.goodfood.com.au/ is also worth a mention: it focuses more on high-end restaurants, but unlike the free-for-all of Zomato, the reviews are written by professionals.
Food delivery services like Menulog, Deliveroo and Uber Eats are handy if you want to get an idea of what's on the menu at most restaurants.
Personally, I use Google Maps a lot because I find the UI far superior to the convoluted mess of Zomato, but there are generally fewer reviews, photos, menus etc.