That inertia is indeed huge. For example, if your library uses RFID but also shares a catalog and their books with other libraries, they'll still need barcode labels (with the same number that's encoded on the tag) so that the other libraries can deal with the items. Barcode scanners are ubiquitous in libraries; RFID readers, not so much.
Also, one of the promises of RFID for libraries has not panned out very cleanly. When a library does an inventory, not only do they want to verify the existence of the books, but that they are _in order_ on the shelf. RFID vendors for libraries promised that you could do this "shelfreading" accurately just by passing the wand across each shelf, but for various reasons the results are imperfect enough that it's not a clear winner over doing it with a barcode scanner. Given the fact that RFID tags have historically been far more expensive than barcode labels, the economics don't pencil out for many libraries to switch to RFID.
Fun fact: the MARC format, used for bibliographic metadata by the majority of libraries that have digital catalogs, included supporting the printing of catalog cards as one of its use cases [1]. To this day a properly maintained library catalog based on MARC could, with some effort, be used to generate an equivalent set of printed catalog cards.
However, printed catalog cards as a backup to the digital catalog have practical problems. For one thing, they are heavy. A full card catalog of a large public library could easily weigh tons [2] and take up space that would be better used for other functions. For another thing, the expense would detract from other library services, and many libraries already suffer from budgetary challenges.
A proper backup strategy is the way with the risk of losing the digital catalog. Besides, libraries have more fundamental problems to deal with regarding the permanence of electronic resources. For example, the fact that libraries largely do not and cannot _own_ the ebooks they circulate causes numerous problems.
Dunno about Oklahoma, but Kennesaw, Georgia, does have a gun ownership requirement, passed in 1982 in response to Morton Grove, Illinois, banning handguns. Kennesaw's neighbor, Acworth, is the one with the rake ownership requirement -- passed in response to Kenneswaw's gun law -- though it is not immediately clear to me whether that ordinance is still in effect.
Near as I can tell, the best that's available is starting with the class(es) you want (e.g., https://id.loc.gov/authorities/classification/H.html for social sciences) and crawling recursively to grab whatever serialization of the RDF you want to consume. There's no SPARQL endpoint for id.loc.gov, alas, but it beats resorting to the PDFs.
https://id.loc.gov/download/ offers bulk downloads of many of the vocabularies, including the subject headings. In addition, individual records of various types can be search for.
Depending on what you're looking for, a _lot_ more is being published by the Library of Congress as Linked Data nowadays, including LoC classification and subject headings. Check out https://id.loc.gov/.
Many libraries [1], including the likes of the Library of Congress and the National Library of Australia, make their catalogs' MARC records freely available via a library-specific protocol called Z39.50. The Library of Congress makes their catalog metadata available in other ways [2][3] and the Internet Archive has a collection of MARC records as well [4]. There are also a couple commercial services that provide them, and publishers, particularly of digital collections used by libraries, will sometimes supply MARC records (though they tend to be low-quality).
> While it would have been ideal to get all the data in MARC & as many other formats as possible, I wonder how true this is worldwide - many libraries don't use MARC or have a digital catalog at all. Maybe there are some ways the data could be processed that make it easier to integrate into such places, but of course local needs/desires will vary widely.
Indeed, MARC is not universal (and for that matter, it wouldn't surprise me if at this point the majority of records in Worldcat were _not_ derived from MARC sources), and there are certainly non-MARC library catalog platforms out there. That said, as the growth of Koha shows, for better or worse MARC has become a close to a global baseline for a lot of libraries.
I know a bit about Henriette Avram and her work at LoC developing MARC, but it of course makes sense that other libraries were thinking along similar lines at the time.
It's not a LibraryThing or GoodReads; it's meant for libraries that are institutions. That said, I don't think there is anything stopping an individual person signing up and entering their collection, but there would be no point in paying the fees unless you had (say) a unique scholarly collection and wanted to lend books to other libraries - and if so, in the long run you'd likely be better off seeing if a library wanted to acquire your collection.
The International ISBN Agency coordinates assigning ISBN ranges to national agencies, who in turn will assign subranges to publishers. The publishers in turn assign specific numbers to their own works. However, the international agency does not itself maintain a universal database of assigned ISBNs - the most it operates is a global database of publishers and their assigned ranges. And since it's the publishers who are assigning numbers from their allocations, various errors can crop up, including reusing ISBNs for different works and failing to issue distinct ISBNs for different formats. (For example, if you publish hardcover, paperbook, and ebook versions of a book, you should assign three ISBNs. That rule is not always observed.)
Also, libraries hold many books that long predate ISBNs; it wasn't until 1965 that the immediate predecessor of the ISBN, the SBN, was a twinkle in a bookseller's eye.
It's not the software per se, which is generally fit for purpose but not amazing, but the traditions and economics underpinning how libraries maintain their bibliographic metadata.
Libraries sharing metadata for their catalogs has a long history, dating back to at least 1902 when the Library of Congress started selling catalog cards for use by other libraries. In the 1960s, the Library of Congress embarked on various projects to computerize their catalog, leading to the creation of the MARC format as a common metadata format for exchanging bibliographic records. (And there is a straight line between how card catalogs were put together and much of how library metadata is conceptualized, although that's been (slowly) changing.)
One problem is that bibliographic metadata from the Library of Congress is mostly generated in-house, and LoC does not catalog everything; not even close. In the late 1960s, OCLC, the organization behind Worldcat, was started to operate a union catalog. The idea is that libraries could download bibliographic records needed for their own catalogs ("copy cataloging") and contribute new records for the unique stuff they cataloged ("original cataloging"). Under the aegis of OCLC as a non-profit organization, it was a pretty good deal for libraries, and over time led to additional services such as brokering interlibrary loan requests. After all, since Worldcat had a good idea of the holdings of libraries in North America (and over time, a good chunk of Europe and other areas), it was straightforward to set up an exchange for ILL requests.
Tie this with a general trend over the past couple decades of libraries decreasing the funding and staffing for maintaining their local catalogs, and need for sharing in the creation and maintenance of library metadata has gotten only more important.
However, OCLC has had a long history of trying to control access and use of the metadata in WorldCat, to the point of earning a general perception in many library quarters of trying to monopolize it. To give a taste, Aaron Swartz tangled with them back in the day. [1] One irony, among many, is that the majority of metadata in Worldcat has its origins in the efforts by publicly-funded libraries and as such shouldn't have been enclosed in the first place. OCLC also has a focus on growing itself, to the point where it does far more than run Worldcat. Its various ventures have earned itself a reputation for charging high prices to libraries, to the point where it can be too expensive for smaller libraries to participate in Worldcat. (Fortunately for them, there are various alternative ways of getting MARC records for free or very cheap, but nobody has a database more comprehensive than Worldcat.)
That said, OCLC does do quite a bit itself to improve the overall quality of Worldcat and to try to push libraries past the 1960s-era MARC format. But one of the ironies of the scraping is that it's not going to be immediately helpful to the libraries who are unable to afford to participate in Worldcat. This is because the scrape didn't (and quite possibly never could have) capture the data in MARC format, which is what most library catalog software uses. While MARC records could be cross-walked from the JSON, they will undoubtedly omit some data elements found in the original MARC.