The scenario works like this: traffic is backing up, especially around merges (I could ramble long and hard on the average Kentucky driver's destructive approach to merging). Some of us think that stopping in the right lane just because someone thought they should merge NOW into completely blocked traffic, instead of rolling forward until there was an opening, is a bad idea. So when that person has their car half into the left lane, we go around them, and find the nice open gaps they created for us. And discover that in front of them, traffic is moving just fine thank-you-very-much.
To sum up: some cars merge immediately, some cars merge later. And therein lays the frustration for the Self-selected Traffic Controller (STC), for he/she (though really, probably a he) cannot stand that some people are "cheating" by no merging immediately, but instead have the audacity to use the other 1500 feet of lane and fine a merge point later on. So what does he do? The STC executes a partial merge, and straddles the lane line. This way he has "merged" obediently, but also prevents others from going around him. If someone should attempt to go around him by using the shoulder, perhaps because they thought he was just really slow to move over and didn't want to wait, the STC may decide to actually remain in the right lane. This however doesn't lose his merge position, because the people in the left lane behind him don't move forward since he has already proven that 1) he is merging 2) he's a dangerous idiot.
To give them the benefit of the doubt, I will assume that STC's do this not only because they are idiots, or jerks, or... OK, benefit of the doubt: they do it because they think it will help traffic move faster. They believe that if we all merged right away and used only one lane (instead of two), it would be faster. Clearly they know little of volume flow, but I must grant that there are plenty of people who race up, then slam their brake, and back everything up on a merge (note previous comment on destructive merging habits). But what I've noticed is that STC's end up driving slower, because they have to dedicate so much attention to watching their review-mirror to make sure they can block the people trying to drive the speed-limit and not 20 miles under it. So instead of making things move faster, things move slower.
I love leaving STC's in my dust.
