Before I read the article, I thought the “bus ticket” was referencing William Sidis, who in the early 20th century gave a mathematics lecture at MIT at 10, a Harvard student at 11, was expected to revolutionize math but then dropped out of the public eye to write strange books, one being an etymology of train and bus tickets across the US, collecting several thousand unique stubs. I bet that you could learn a lot about the flow of ideas and culture in the US from such a strange artifact, and while I agree with much of what PG says here, his definition of utility leans towards the economic sense. Also of note, Knuth has a section on his website devoted to photos of traffic signs!