I don't even think it would be even a blip on the radar now.
It really is depressing how much ground we've given.
My local library is run by the county government, so of course the government can see the checkouts, they are the ones I check the book out from. But they restrict checkout information from others. For example, a parent can see the checkouts of their own children, but not after they turn 13.
Perhaps you're talking about subpoenas? Checking some other libraries I see SF Public Library has some discussion about that, but they delete books from your checkout history once they are returned. https://sfpl.org/about-us/confidentiality-and-usa-patriot-ac...
...I mean I suppose you still can but still, it's not as obvious anymore and people's mobile phone numbers are unlisted by default and not publicly linked to an address..