Public busses are prioritised through various mechanisms such as advanced starts from traffic lights or exclusive lanes, but Australia (and Melbourne) add an additional simple road rule to ensure a bus cannot get stuck waiting for a gap in traffic. Which was distilled into the rather elegant sign affixed to all public busses:
The road rule as current in Melbourne is similarly unambiguous.
77 Giving way to buses
(1) A driver driving on a length of road in a built-up area, in the left lane or left line of traffic, or in a bicycle lane on the far left side of the road, must give way to a bus in front of the driver if
(a) the bus has stopped, or is moving slowly, at the far left side of the road, on a shoulder of the road, or in a bus-stop bay; and
(b) the bus displays a give way to buses sign and the right direction indicator lights of the bus are operating; and
(c) the bus is about to enter or proceed in the lane or line of traffic in which the driver is driving.
Penalty: 5 penalty units.
So how does this work in practice? For Melbourne it does not work at all.
Despite the bus sitting with its indicators on well ahead of the start of this short video, and there being ample space for the traffic to use the other lane they choose to block the path of the departing bus. Laws without enforcement are worthless.