Yes, question banks exist. I'm talking about the company I work for and in fact all the companies I have ever worked for. We did not use question banks.
Your claim was most companies though but to be fair, you are more accurate.
Most of The big tech companies that are viewed heavily on levels.fyi definitely has question banks.
And there are definitely question banks. I saw my team go through (the company recommended lists) in a meeting and we selected some questions