Sure, if you only care about America. But people in other countries read books too.

Here's the best selling book in Germany:

https://www.goodreads.com/book/show/45006237-das-geschenk

Oh, hm, ISBN is probably better? These guys seem to have a DB, wonder how they get it? https://isbnsearch.org/

It used to be that authors needed to deposit a copy of every new book at USLC, that's probably an old thing.