So, can I publish a book in Denmark, say it costs 1,000 dollars, and your libraries will be forced to buy it just because they have to make "all Danish published material available."?? There must be some sort of guidelines (though seeing how Swedish law works I wouldn't be surprised you guys just "trust" people to price things correctly).
All publishers are required to supply one copy of any published book to the royal library (for free).
Individual libraries are not required to buy any particular book. They have a fixed budget for buying material and will decid based on quality and expected demand.