After spending a fair amount of time driving in every other state, I don't blame the Perth drivers so much for their failures. I reckon it is more to do with the road design and signage.
In Queensland, the incoming merging lane is well signposted before it makes it to the freeway. Once there, there are a hundred signs letting you know the lanes are merging and to give way to people entering. They are also very long which gives people time to recognise the situation. With all the communication, people understand what is needed to happen and it works. People merge succesful at the speed limit and traffic flows.
In victoria, there is fuck all signage. When the lanes merge, they come out of the blue with no indication whatsoever. All of a sudden that four lane highway you were travelling on is now 2 lanes, one of which is turning off in 20m again with no indication. As such, Victorians can't drive for shit. They can't follow the rules so they just create their own.
Perth sits in between the two. The merging lanes are there but far too short. The signage is there, but not until the last minute when you should have already completed the merge. I find the majority of the time when my lane is merging, if I don't know the stretch of road very well, I won't even realise my lane is merging. This is where the problem lies. Unless you drive the freeway daily, you don't have any idea that you're supposed to give way until it's too late. Then the brakes go on, everyone slows down, the merging lane gets road rage, grannies sit in the right lane to avoid the problem and all hell breaks loose.
My proposition to solve the problem is longer merging lanes. MUCH more signage, big fat overhead bill boards with drawings showing your lane is merging and a picture of a zipper so people understand how to do it.... And more lanes
Some of the on ramps are quite messed up as well. I've seen a few where the off ramps are the on ramps are combined. So the people exiting the freeway are mixed up with the people trying to get ON the freeway. and they both have to somehow switch lanes amongst themselves to get where they're going. That's just plain shit road engineering.