I think it's intentional. A lot of creators of computer display technology (physical) and computer vision based algorithms use a "standard image set" to present their invention's performance against a common benchmark, like the image of "Lena" (1). There's also standard benchmark images of a parrot, a tea pot, a bowl of fruit and a rabbit that I see often.
This makes sense and we see the Lenna and Utah teapot everywhere for things like 3D rendering and compression. There are equivalent datasets for evaluating cv models - you see them benchmarked against coco a lot, for example.
I still am surprised to see all the same images and diagrams in the -explanation- part of so many papers. It feels like early word processor days and everyone using the same clip art.
1. https://en.wikipedia.org/wiki/Lenna