Language doesn't work that way. Being prescriptivist about it doesn't change that language evolves. The time to have had this fight about "banned books" was 40 odd years ago, and you still would have lost it because your interpretation being limited to a "country-wide ban" is also nonsense in a meaningful sense. If a political figure has made a decision that a book will not be available in the places where it would otherwise normally be available for people for whom that political figure has some level of control -- and that unavailability is for purely political reasons -- it's perfectly sensible to call it a book banning.
There are books and magazines banned in prison libraries. Because it's prison, those books are also considered contraband if a prisoner's family delivers it to them. This is a book banning. One may argue whether it's a good thing or a bad thing, but it's a book banning.
If children would _normally_ have access to age-appropriate books in a school library about same sex marriages (Suzie's Two Dads or Johnny's Two Mommies or whatever) but some retrogressive numbskull politician in Florida decides that teaching kids about same sex marriages is wrong and therefore those books are no longer allowed in school libraries, it's a book banning. If the child brought said book from home because they have two dads or two moms, they'd also probably land in trouble because school administrations are conservative and CYA in nature.
If you actually cared about words and their meaning, you wouldn't try to insist that there's only one correct meaning. Language evolves.
Wikipedia: Book censorship or book banning is the act of some authority (countries, government) taking measures to suppress ideas and information within a book.
More Wikipedia: According to the Marshall University Library, a banned book in the United States is one that has been "removed from a library, classroom, etc."[19] In many situations, parents or concerned parties will ban or propose a ban on a children's book based on the book's contents.[20] The American Library Association publishes a list of the top "Banned and Challenged Books" for any given year.[21] The American Library Association also organizes a "Banned Books Week", which is "an annual event celebrating the freedom to read."[21] The goal of the project is to bring awareness to banned books and promote the freedom to learn.[22]
All that's required for a "ban" to be a ban is an official act to prevent or prohibit someone from doing something. In the case of school book bans, it's to prevent teachers or school librarians from exercising their skills and judgement on introducing books for kids to read. Sometimes this is justifiable, most of the time it is not.