Income earned from the sharing economy, AirBNB, Uber, AirTasker etc., must be declared in your tax return. But you may also be able to claim proportional expenses associated to providing the service. Ensure that any deductions you claim are related to providing the service itself (not just switching on the app or making yourself available).
If you are a driver with Uber or another platform, you will need to be registered for GST regardless of how often you drive.