I suspect that many of these people are being paid by SEO companies to build links to websites, presumably in Australia. That's fine, if they get the job done. But it may be an issue for some Australian business owners who use these services.
Firstly, they may not like the idea that the work is being outsourced. Also, as much as I'd like to say otherwise, they may be disappointed by the grammatical quality of these submissions. English is an official language of both countries. However it's not the main one as it is in Australia. So citizens of those nations are generally less confident with it.
I suggest this may be something to consider if and when you decide to purchase an SEO package.