Why is it that any time you have construction on the highway, people feel inclined to merge into one lane a mile before the lane is blocked off? More importantly, why is it that when people merge early, they feel that the cars behind them should be obligated to merge when they do? Countless times I've seen some asshole pull out of the merged lane to block people from passing by, which they have every right to do as long as the lane is still open.
What authority do they have to decide when it's appropriate to merge, especially when there are cones and arrows conveniently placed on the road for this purpose??
When traffic merges early, it adds to traffic buildup. It causes traffic to move more slowly through the construction. Furthermore, it adds an element of danger when people merge (and unmerge) based on their own whims. It's faster and safer to wait until you've reached the point where you are instructed to merge.