I find the interview process at Google/Facebook extremely disturbing for senior devs like author of Homebrew. Nobody can remember how to manipulate binary trees

I find the interview process at Google/Facebook extremely disturbing for senior devs like author of Homebrew. Nobody can remember how to manipulate binary trees/linked lists/(un)directed graphs after working on real world projects for several years. Why can't you just interview like the rest of the industry? I understand some deadwood might get in this way; just simply fire'em after several months on the job. Netflix is an excellent example in this regard.