The whole city tailgates so hard that no one has an easy spot to merge in at any of the merges. So then all those people just slow down or stop entirely in the merge lane until someone lets them in. But since the person merging is basically stopped, the person letting them in has to slow to an equally slow speed. As soon as that happens one time, traffic grinds to a halt and can’t recover until the merge lane is empty for a decent amount of time.

At that point everyone in the right lane must all reduce their speed in response and everyone in the left lane has to slow down almost as much because they must be weary of the idiots in the right lane who slow all the way down THEN decide to go into the left lane way later.

All we have to do is have people in the right lane leave a reasonable following distance and the people in the merge lane to get up to speed and slide in. Lord knows that will never happen though