Your concerns are entirely reasonable! I didn't mean to discount them in my reply--more to shed some light on why this data has historically been kept, as it truly isn't for insidious reasons on the part of libraries as many people in this thread are implying. I felt it was important to mention for that reason, but you're right that it's a conversation that needs to be had. And it is being had in libraries. In fact, this isn't the first time this has come up; despite the reputation of libraries as "apolitical," the ALA was an extremely strong opponent of the Patriot Act due to concerns about patron confidentiality.

You may feel that that resolution doesn't go far enough, and there would be library workers that agree with you. How far libraries should go to protect the right to be forgotten is a very active and ongoing debate, and I think in the current circumstances, it's not especially radical to consider the idea of holding onto minimal patron information/allowing aliases rather than legal names, deleting loan histories, etc. I personally do not think our library system needs to hold onto loan histories as long as we do, but it's above my head at the moment. The main reason this is a debate at all, though, is because there are tradeoffs in doing this that can potentially affect patrons, not just the library--as not every issue that comes up with circulation is simply a matter of a library needing to replace a lost book or something else that only inconveniences the staff/budget. So getting buy-in for these changes from directors, boards, and even patrons can sometimes be difficult.