There are a few reasons why Australia has this law. First, it helps to keep traffic moving smoothly. When all vehicles are driving on the same side of the road, it is easier for drivers to see each other and avoid accidents. Second, it helps to prevent confusion. If there were both left-hand drive and right-hand drive vehicles on the road, it would be more difficult for drivers to know which side of the road to drive on.
If you are planning to visit Australia, you will need to rent or purchase a right-hand drive vehicle. You can also bring your own left-hand drive vehicle into Australia, but you will need to have it converted to right-hand drive. This can be a costly and time-consuming process.