Many new books are not made available as ebooks and when they are, they are often available only as Kindle books and other very restrictive formats.
Publishers make decisions about how they publish to maximize their sales and profit, but it's not clear how to do that. They might like to sell a copy to every single person, although libraries are reliable buyers.
Publishers also have their own unique histories and cultures.
The result is a wide variety of practices and openness to the library market.
Sometimes, publishers change their assessment of what will help them most and make an ebook more or less available.
Sometimes an ebook is available at a reasonable price with reasonable restrictions and we can buy it. Other times it's not.
When it is, the library still has to decide. Does our community need this book? As an ebook?
Oxford Scholarship Online offers access to over 4,200 Oxford eBooks in Biology, Business and Management, Classical Studies, Economics and Finance, History, Law, Linguistics, Literature, Mathematics, Music, Neuroscience, Philosophy, Physics, Political Science, Psychology, Public Health and Epidemiology, Religion and Social Work.