People used to zipper merge where I live... in the 80s. But the metro region I live in is much more dense than it used to be, and combined with the fact that th

People used to zipper merge where I live... in the 80s. But the metro region I live in is much more dense than it used to be, and combined with the fact that the police don't spend a lot of time enforcing traffic laws, and that the public transportation system has poor coverage, traffic problems have skyrocketed. One of the reasons why people early merge here is that many people don't let mergers in. And one of the reasons why people don't let mergers in is that they regularly get cut off by a second car after letting a merger in. It's a vicious circle. Back in "the day", zipper merging wasn't even an issue. A lot of people early merge here because they'd rather be the one letting people in than hoping to be let in.