@matigo True. Does nothing for productivity. Actually increases energy consumption. And messes up business between eastern & western areas.
Sydney/Melbourne are normally 2 hours earlier that Perth, DST will make that 3 hours as WA doesn't participate in the silliness.
When the office opens in Perth, head office out east is going off to lunch, so there's two hours available for stuff until the western lunch hour. By the time Perth is back from their lunch at 1 pm local time it's 4 pm out east. Leaving about another hour to get stuff done.