When I was much younger (pre-teens and teens), I was a voracious reader and would spend a lot of time at the library. But even there, I would mostly stick to the long-running series that I knew well, or prolific authors that I knew I liked.
Some places feel "well-curated": they may not have a ton of books, but it seems like the books they do have were carefully chosen. Maybe there are "theme" collections (local authors, ghost stories for grownups, Russian authors", etc) or well-read staff members making recommendations. I love browsing these places.
Other places seem to go with the "pile of books" approach. There's a lot of them, roughly organised ('fiction') and many of them are obvious tat ('Lose Weight the Dr. Oz Way' or something. I find it easy to leave these places without buying anything.
Instead, the thing that got me to use Amazon was that it provided you with access to a long tail of books—and later, other stuff.
Bookstores and record stores did do "special orders", but there was a lot of friction in the process. You'd have to find out about the book, visit the store (twice!), and if what you wanted was even available, you would wait a few weeks for your order to be bundled in with the next shipment from the publisher.
Amazon removed all of that—and the reviews even made it less risky. Want to read the next book in a series? Check out the reviews and if you want it, done deal! Need some obscure technical title? It'll be AT YOUR HOUSE next week.