Zipper merges are just another thing for engineers to say it works perfectly when the reality is there are too many variables and egos involved for it to work properly.
Yeah, because we have people like this:
I’m that guy where, when a lane is closing and people are supposed to zipper merge, if people keep trying to zoom past and up in the other lane, I’ll just pull into it and continue at the same speed I was going before so people can’t cut. Not once have I ever had the car that was originally behind me in the lane people are supposed to merge in to not let me back in to the merge lane once the closing lane officially closed. I have had one car drive into a ditch to still go around me once, though.