In the Netherlands competing with discount is actually illegal, interestingly enough. The selling price is fixed. Which is a boon for smaller bookshops, but annoying for publishers if the production prices aren't stable.

The unit cost for the publisher to put a $20 AUD book on a shelf in a book shop was about $2 AUD.

The bookstore kept quite a bit of that margin - $10 or so - but they had to pay rent & staff a store. If they were only selling $500 worth of books per day, it wouldn't have mattered if their margin was 100%, the fixed overheads would eat it all. If they could keep stock turning over quickly, the profits were impressive.