.com.au domains and ABN

Do you need an ABN?

[gecko1]

I was wondering if it is really necessary to have an ABN to get a .com.au domain?

[leadegroot]

Generally, yes, it is, however there are other ways, such as a Registered Trading name (I am fairly sure of this)

If your question is a more general 'do I really have to be operating an actual business?' then, yes, you do.
In theory the registrars are supposed to check each registration request - the process is not automated.