Somebody wrote “I think the logic of conventionalism is coordination.” That was interesting, so I did some excavating.
Tracing it back, I think there are two underlying reasons why we often follow cultural conventions whether they make sense or not. One, we are a social species. And two, like all animals, we have slow neurons.
Starting from the end, slow neurons mean that we have to keep computation paths short if we are to react in real time, so we are forced into a knowledge-dominant strategy for intelligence (as opposed to computers which tend to be more successful with heavy use of computation). Humans remember quickly but reason slowly, and we will always have an easier time with the familiar than with the new or different that our knowledge does not apply to. (That explains why we value creativity: We are low on it.)
Being a social species means that we can save effort by learning from each other, rather than figuring things out for ourselves. Copying from each other means we end up following conventions that we may not understand the original reasons for. And cultural learning is successful, so as it happens more, evolution reinforces it.
Other stuff ties in, but I see those two points as the most fundamental. Cultural learning supports the hardwired in-group/out-group and social status evaluations that have been (and likely still are) driven directly by evolution since before the origin of genus Homo. Your culturally learned speech and dress and many other behaviors are co-opted to identify your social group; that is a form of coordination. Standardization is another form, and makes cooperation easier. These I see as secondary adaptations.
Rush hour is perverse coordination.
Original version, August 2014.
Updated and added here February 2021.