I was going to do the exceptions to the no-talking rule in a separate advanced course. It's perfectly acceptable to share a space with someone and not say anything for twenty years..... THEN, if something goes wrong and the train is delayed or the bus doesn't show up, you can explosively agree with each other and have an animated discussion. Once the problem is resolved you need never talk again and you can return to another 20 years of silence, but this time content you have made an acquaintance with a commonality of purpose.

We're weird.