And book stores have always been separate from libraries (public or otherwise) since the time of the Alexandrian Library:
Bookselling is the commercial trading of books, the retail and distribution end of the publishing process. People who engage in bookselling are called booksellers, bookwomen, or bookmen. The founding of libraries in 300 BC stimulated the energies of the Athenian booksellers. In Rome, toward the end of the republic, it became the fashion to have a library, and Roman booksellers carried on a flourishing trade.
The spread of Christianity naturally created a great demand for copies of the Gospels, other sacred books, and later on for missals and other devotional volumes for both church and private use. The modern system of bookselling dates from soon after the introduction of printing. In the course of the 16th and 17th centuries the Low Countries for a time became the chief centre of the bookselling world. Modern book selling has changed dramatically with the advent of the Internet. With major websites such as Amazon, eBay, and other big book distributors offering affiliate programs, book sales have now, more than ever, been put in the hands of the small business owner.
In the course of the 16th and 17th centuries the Low Countries for a time became the chief centre of the bookselling world, and many of the finest folios and quartos in our libraries bear the names of Jansen, Blauw or Plantin, with the imprint of Amsterdam, Utrecht, Leiden or Antwerp, while the Elzevirs besides other works produced their charming little pocket classics. The southern towns of Douai and Saint-Omer at the same time furnished polemical works in English.
Queen Elizabeth interfered little with books except when they emanated from Roman Catholics, or touched upon her royal prerogatives; and towards the end of her reign, and during that of her successor, James, bookselling flourished. So much had bookselling increased during the Protectorate that, in 1658, was published A Catalogue of the most Vendible Books in England by William London. A bad time immediately followed. Although there were provincial booksellers the centre of the trade was St. Paul's Churchyard. When the Great Fire of London began in 1666 the booksellers put most of their stock in the vaults of the church, where it was destroyed. The Restoration also restored the office of Licenser of the Press, which continued until 1694.
In the first copyright statute, the Statute of Anne (1709), which specially relates to booksellers, it is enacted that, if any person shall think the published price of a book unreasonably high, he may make a complaint to the Archbishop of Canterbury, and to certain other persons named, who shall examine his complaint, and if well founded reduce the price; and any bookseller charging more than the price so fixed shall be fined £5 for every copy sold. Apparently this enactment remained a dead letter.