There are a multitude of problems generated by failing to maintain lane discipline and the most important would probably have to do with safety.
However, it’s plain rands and sense that I concern myself with here.
Modern freeways rather obvioulsly have the massive benefit of ensuring that all traffic is moving in the same direction. When used in conjunction with the “keep left, pass right” law, freeways are able to move very large volumes of traffic at relatively high speeds safely, when compared to two-way roads.
But they are vastly expensive to build, particularly when unneccessary toll structures are included.
One wants therefore to build only the road that is necessary for efficient commuting.
If we do not move to the left after passing a vehicle the efficiency of freeways is drastically reduced. When cars doing more or less the same speed use two or more lanes, lanes are effectively being wasted.
Cars wanting to travel more quickly are unable to do so and so queues form in lanes and traffic congestion develops rapidly. Look the next time you are on a fairly uncongested stretch of freeway at how much open space there is over and above that necessary to maintain a safe following distance between cars.
That is effectively unused road, road that should not have been built if motorists adhered strictly to a pass left and, when safe, move right strategy.
If there is space to the left of you that you could safely be occupying, you are in the wrong lane – and that space is wasted.
But what about rush hour jams, you ask? Fair point. But remember, barring incidents like breakdowns and accidents, jams build up gradually.
The better we use the available road space, the “better” the traffic jam.