Oh, you definitely can. You're just unlikely to be able to find them without already being involved in crime

The ID verification methods vary to account for channels like that you can buy SIMs from vending machines at airports and train stations and verify online https://www.acma.gov.au/theACMA/approved-methods-for-verific...

Vodafone just let you tick a box saying "i am who i say i am" https://www.acma.gov.au/Industry/Telco/Carriers-and-service-...