For me, the question asked should be "why wouldn't you hire an Australian virtual assistant?"
If your business is made in Australia and runs in Australia, with Australian clients, then it stands to reason that you would want to outsource your administration|social media|marketing to someone that understands you: not just the language.
Understanding you, in my humble opinion, means listening to your business model, treating your clients as if they are your own, learning how you operate and how you speak, how you run your business and deal with others, what your branding is and what you stand for, along with many others.
If you are taking the time and the money to hire someone in your business, wouldn't you want someone who cares about your client? Wouldn't you want someone who can speak to you in your timezone? How about understanding your slang words or nuances in your speech?
An Australian VA will operate under the same laws as you do and will carry insurance to protect themselves and you, as their client. They can have a conversation with your clients, if required. We can also often be available 'in person' if required for additional support.
For example, I have attended networking events with my clients to ensure they have backup with systems and processes, and even to hand out drinks and assist with cleaning up at the end of the night.
So, again, why wouldn't you hire an Australian virtual assistant? I would love to hear your thoughts on this.