Why do book spines have the titles printed the way they do?

Have you noticed how the titles printed on the spines of your books are all, for the most part, oriented the same way? That's not a coincidence.

ISO 6357 defines the standard positioning of titles on the spines of printed books (it's also codified as British Standard BS6738). If you assume

https://danq.me/2019/01/27/iso-6357/