Do these people really think we're all queuing behind an elderly Honda driver struggling to overtake the truck for our own good? Possibly some sort of vision problem leads to them being blissfully unaware of the fact there were already half a dozen people waiting to do so?
Whatever the problem, it never fails to amuse me. It's not so much the matter of bad manners (although this undoubtedly applies to subsequently trying to force their way into the outside lane) or that it's technically illegal. No, it's more the fact that doing this is so obviously counter productive. The inevitable outcome is that they stay moored behind the truck until the (now enlarged) stream of traffic in the outside lane clears. Had they looked more than two cars in front, this result would have been clear, but a total inability to plan ahead masks that from them.
Undertaking in general is a whole other can of worms – I appreciate you do sometimes get people doing 50mph along the outside lane of an empty dual carriageway and this is a different matter. However, they both have a common cause – poor lane discipline. If everyone pulled back in after overtaking slower vehicles, without holding up those behind them, neither would occur.
Linked to this is the failure on the part of some motorists to grasp a very simple concept - namely, that you must be travelling faster than someone else to overtake them. This may sound like the preserve of 'lorry races', but the number of timid drivers who attempt to overtake people doing 65mph at precisely 65.5mph is another cause of motorway congestion.
What really gets me is that none of this is brain surgery. It's simple logic that anyone with half an ounce of common sense should be able to take in, yet something causes otherwise intelligent people to blank this from their mind whilst in the car. Maybe it shows the grasp that driving holds on our minds or, maybe, this mental shutdown is a product of motorway monotony. Thinking about the latter, perhaps the government should subsidise us all to liven up our commute? Get to work in a TVR? That'll be ten points. Covered fifty miles of B-roads in an Elise on the way in? That'll be fifteen. We can but dream.