The alternative to the zipper merge is the “nobody is sure how far back they should merge merge”. You still get the people losing their temper over watching people repeatedly merge in front of them, or getting mad at the undoubtedly Canadian asshole in front letting people in (source: I’m the actually Australian…

Back in the early ‘80s Nicolai Shapiro (author of the SF tabletop role-playing game “Other Suns”) used to talk about the problems of allergic reactions, and the likelihood that any extraterrestrial ecosystem would cause horrible allergic reactions in most terrestrial species.