Z-Library has been innovating a great deal in that regard. Sadly they are not as open/sharing as LibGen mirrors in giving back to the community (in terms of database dumps, torrents, and source code).

Have you ever used a card catalogue?

No. Your point being?

In that case your expectations are understandable. People in your generation are accustomed to finding anything in mere seconds. Not very long ago, if it took you a few minutes to find a book in the catalogue you would count yourself lucky. And if your local library didn't have the book you're looking for, you could spend weeks waiting for the book to arrive from another library in the system.

Libgen's search certainly isn't as good as it could be, but it's more than good enough. If you can't bear spending a few minutes searching for a book, can you even claim to want that book in the first place? It's hard for me to even imagine being in such a rush that a few minutes searching in a library is too much to tolerate. But then again, I wasn't raised with the expectations of your generation.