I work for a large company that hires a lot of developers. If you're in the US you've heard of us and there's maybe a one-in-three chance you're our customer. We are not "sexy" though. I have seen question banks circulate occasionally but when it's time to actually interview nobody can ever remember where the question bank is. Usually when I've been on a team that's actively hiring we make up a bank of questions for that particular round of hiring, which helps us in comparing those candidates that are directly competing against each other. But nothing at scale.