so in Brisbane Australia, most drivers of non two wheeled vehicles these days make space, but like the UK there is always some twat that doesn't like the motorcycle guy/girl getting ahead or still thinks it's an illegal manouvre.
It is legal to split lanes here in the State of Queensland, but you may not exceed 30kph and only do this when safe to do so. Some muppets still think your breaking the law.
"Overtaking on the left" or in an "unmarked lane" as the Police Traffic Branch refer to it are both offences and attract a fine and points.
So running down the left side of a left lane on say a motorway or "riding the shoulder" as it's commonly refered to, is illegal.
Ask me how I know all this
Unfortunately there are a group of riders who must persist in higher speeds whilst lane splitting, in my opinion that makes all motorcycle riders look bad.
I commute to the CBD in a large 4x4 Utility and in the last 2 years have been witness to two separate incidents where riders "clever, skilled & very confident types" who came to an unfortunate and rapid halt resulting in smashed bikes & other vehicles and injury to themselves after hitting vehilces whilst executing very high speed lane splitting.