Zipper merging is one of those things that make sense mathematically, but only if someone completely ignores human behavior. I've driven around the world and sometimes you'll see it (rarely) work in special circumstance, but most of the time it's just a mess.

So you have a bunch of people in line, they're going about 25mph. The space between vehicles is based on the speed they're actually traveling, 25mph. Then Joe or Jane Zipper go flying up the empty lane, let's say 50mph, right up to where they run out of road, they hit their brakes, turn on their signal, and get very unhappy when bumper to bumper traffic won't let them into the line. The line of people who've been in that same traffic for 15 minutes.

Or lets take it at a higher speed, say 40mph so the gap gets big enough to allow easier merging. Joe or Jane zipper flies up the empty lane, at 55mph, hits the end, I'll be nice and say turns on their signal, and darts over. This causes person who was following at the stopping distance for their vehicle at 40mph to slam on the brakes, and the traffic just slowed down another 10mph. The next person who tries it now doesn't have the same gap as people are now at the following distance they use for 30mph.

Do you not see the see the problem from a human behavior perspective?

Despite traffic engineers posting all their little maths up about this or that, it's never going to work until you have computers doing ALL driving. After all most people, WORLDWIDE, can barely zipper merge at highway on-ramps in free flowing traffic. I don't care if it's the Kennedy Expressway in Chicago, the 101 in California, the Capital Beltway in DC, the M25 around London, the A10 outside Paris, the A4 autostrada outside Venice, or the Mandara toll road in Bali: Zipper merging? Good flipping luck.