Any answers to a very good question? Because of a particular mindset which holds that if it's imported it has to be better.
For my thinking why can;t we find good capable Australian Management for V/Line?
Well by that yardstick, there goes most of the VR Chief Commissioners in the 19th and early 20th Century then (think Speight, Tait, Clapp, etc) and most Australian railway management in the same period (think Whitton, Thow, Webb and many others). It took generations to develop local management skill.
The other, more confrontational thought is that the local pool of management talent is no good, so competent people have to be hired in from elsewhere to do the job.