Lane straddling doesn't prevent people merging via the zipper rule. Rather, it prevents people already on the road from moving over to the merging lane, shooting ahead of a bunch of people, then merging again (slowing down everyone else by adding to the merging traffic). It's one of those behaviors where whatever convenience that person gets is greatly outweighed by the cumulative cost to everyone else.
Actually lane straddling doesn't even work to prevent someone from using the zipper rule. It prevents people from passing other people on the right (nobody should be passing anyone on the right most of the time anyway). But it doesn't prevent someone from merging into the other lane when the time comes. As long as you're pacing yourself vs. the speed of the traffic in the lane you want to merge into, everything's fine. Using the zipper rule doesn't mean you race ahead of everyone before merging, if anything it means waiting a little bit longer and maybe even merging behind a car you would otherwise be tempted to merge in front of.
Straddling prior to zipper merge at the last moment is absolutely intended to prevent proper zippering, which you would describe as "shooting ahead on the right."
Maybe I'm wrong, but my understanding is that proper zippering is simply waiting until the lane ends to merge. You align the right side of your car with the curb and let it weave you into the lane at its own pace. It doesn't necessarily involve speeding ahead to get to that point, although certainly lots of people do that. It minimizes the jostling and speeding up and slowing down that people do to try to actively find a place to fit in.
When traffic is at its peak, it approaches its ideal state: the on-ramp is fully occupied with cars (no space wasted), and everyone's driving at basically the same constant speed up to the merge point, where everyone neatly and cleanly merges, alternating lanes. But if traffic is not at its peak, zippering doesn't require you to race ahead to merge point.
It wouldn't hurt anyone if you did that, of course. Same for everyone else waiting to merge. But there really are lots of people (where I drive at least) who are already on the road/freeway/whatever, who will move onto the (about to end) merging lane, race up to the end of it and force themselves back on the road, a few cars ahead. I've seen so many bad traffic jams made so much worse by people doing this. It makes a bad situation so much worse for everyone. Those are the people the straddlers are guarding against, not the well-mannered zipperers trying to do the right thing.
Your earlier comment misunderstands zippering (IMO). This one starts off less problematically but still ends with the wrong understanding:
> But there really are lots of people (where I drive at least) who are already on the road/freeway/whatever, who will move onto the (about to end) merging lane, race up to the end of it and force themselves back on the road, a few cars ahead. … It makes a bad situation so much worse for everyone. Those are the people the straddlers are guarding against, not the well-mannered zipperers trying to do the right thing.
This is basically incorrect. Regardless of how you and straddlers feel about this, using up that empty merge lane on the right is more efficient than straddling or other forms of early merging. That's my understanding, anyway.
The point of the article is that your intuition is incorrect. By inhibiting zipper merging you are forcing congestion backward, and leaving carrying capacity of the road unutilized during congestion when it is most at a premium.
Pushing congestion backwards is exactly the cause of a lit of traffic jams. I've observed this myself every single GD day on the 210W freeway between Hill exit and the 134 exchange. People get over way early, causing huge congestion to the merge entrances. If they'd stay left and zipper, everyone in the jam would save about 5-10 minutes. This is thousands and thousands of dollars a day of cost in completely avoidable congestion in just one two mile stretch of highway ( albeit it a particularly egregious one)
I'm not normally one to complain about downvotes but I literally cannot imagine how any of what I wrote was remotely controversial. Like I'm trying to look at it with different interpretations and perspectives and I'm just not seeing it. I've seen hotter takes in DMV driving guides. I'd be very curious what the disagreeing opinions are and why. For the record, I've never straddled lanes, I was just explaining why people do it.
In the ideal scenario of lane straddlers, everyone trying to enter a particular lane at a particular point has to do so at the end of the line of people already waiting to enter. The right hand lane is completely unused and therefore the length of the line is double what it needs to be, possibly so long that it interferes with other intersections.
In the ideal scenario of zipper merging there is no free right hand lane to shoot ahead in: it is completely filled with people that are alternately taking turns with the other lane to enter the merged lane. The queue is half the length in this case then the prior case. The lane straddler doesn't feel taken advantage of since everyone is entering the queue in the first available location (left or right).
Lane straddlers perform an illegal maneuver (I assume intentional driving in two lanes is illegal in most countries) to pre-empt the more efficient usage of the road. Their righteousness is unjustified: the person that would otherwise pass them in going to the front of the lane would be increasing the utility of the road. They would be more considerate by entering the lane they are blocking and going to the front themselves.
I certainly see it sometimes. I also see people preventing it sometimes by straddling both lanes.