[reader_x]

The librarians I know are adamant about keeping private the records of what patrons have checked out or searched. I don’t know the history you refer to, where library records were used to identify certain sections of society. Where can I read more about that?

[dijit]

Here’s some entrypoint: https://www.onb.ac.at/en/more/about-us/timeline/1938-politic...

It seems annoying to search for, so I don’t blame you for not finding anything.

[matwood]

It's not just librarians, but many states have laws protecting patron privacy around what they have read.

https://www.ala.org/advocacy/privacy/statelaws

[Larrikin]

The first sentence tells you what to look for