19% is the regular value added tax in Germany. Almost everything is taxed at that rate. Luxury tax is a thing but not in Germany. There is no luxury tax in Germany. There are a very few exceptions for some goods that are taxed at a lower rate. These are by and large basic necessities, public transport and copyrighted works. Books are one example of the last category, but books also have a mandatory fixed book price [1], so their price is not determined by supply and demand.
[1] https://en.wikipedia.org/wiki/Fixed_book_price