Comment by alightsoul

A lot of the rare books seem to be books that are most relevant to specific professions within specific countries. I would expect university or national libraries in those countries to have copies of those books, but they often do not digitize them because controlled digital lending is seen as a legal grey area at best. So these ai companies are doing digitization for them and not publishing it, duplicating work for these libraries once they do decide to digitize.

Many other rare books are just rephrasings of other books on a given topic and this can be done with synthetic data generation now. Same goes for websites

Honestly this feels like a US exclusive problem. Like shipping from overseas would be way too expensive for the cheap books they want. The Chinese just use Anna's archive instead