And I thought smart people worked at the library

If in the real world, the average price of a new book is about $30 (unless you've ever had to buy text books...then I'd say it's about $100+) and the average price of a new movie is about $25, why does the library charge you 25 cents/day when you are late returning a book, yet has the audacity to charge you $2/day when you are late returning a movie?

Which Einstein came up with this formula?