All the optimisation that is put into traffic flow can be eliminated with just a minority of selfish and impatient drivers. Uniquely in Australia to Melbourne is the equal part dangerous, illegal, and inefficient zero clearance merge.
Should there be an obstruction in your lane, there is no need to worry about other road users its custom to simply divert into their lane without care. Whenever you wish to change lanes simply push your vehicle into other traffic and let them worry about getting out of the way:
Comedically the first example is from the contractors (citywide)who recently appeared here having failed to repair a deteriorating waterfront path. But back on topic we can check the road rules for how such a situation should be resolved:
148 Giving way when moving from one marked lane or line of traffic to another marked lane or line of traffic
(1) A driver who is moving from one marked lane (whether or not the lane is ending) to another marked lane must give way to any vehicle travelling in the same direction as the driver in the marked lane to which the driver is moving.
Still the very simple rule of giving way to all other traffic whenever crossing lines on the road but along with many other rules they are so seldom enforced by the Victorian police that some drivers will ignore them routinely. Merging is already an incredibly inefficient process and reduces throughput on roads but queuing patiently in situations such as these leaves the law abiding drivers at a crawl compared to those pushing ahead. Consider just a short queue where drivers are merging both at the stopped vehicle (blue) and further back into the queue.
Drivers patiently joining the back of the queue will be pushed back in order by those drivers carefully merging ahead of the obstruction, and then again as the most inconsiderate drivers continue ahead and force a (dangerous and illegal) zipper merge as seen in the above videos. All the while the queue will extend and only encourage the behaviour more, the worst kind of positive feedback. A co-ordinated zipper merge is relatively efficient as it minimises the stop-start behaviour of queues by keeping both lanes as queues of minimum length, but diverging to these free-for-all situations leaves aggression to sort out the queue.