Sunny,
One could also ask, if a foreign company can send aircraft to Australia for work, what's to stop an Australian company sending an Australian aircraft to a foreign country to work?
The answer is there is no way they could compete in a foreign market under Australian regulations.
Under Australia's unique maintenance regulations it costs twice as much to maintain the same aircraft here as there.
Those that interpret Australian regulations would have you tied up for years writing manuals to prove compliance.
If you manage to remain solvent and sane long enough for an approval to be granted, that can all change with a change at the whim of the new "approvees".
Sovereign risk I believe they call it, with all your key personnel felons and therefore unable to travel overseas, your business model is suddenly dissolved by a pineapple inserted in an orifice, with severe prejudice.