While that's true, it's probably because gov and edu domains are strictly regulated. I could imagine google giving higher priority to .book addresses, provided

While that's true, it's probably because gov and edu domains are strictly regulated. I could imagine google giving higher priority to .book addresses, provided that (a) the user was searching for a book and (b) .book addresses required that the registrant prove that they're the author/owner of a book/book series. In that case, it'd make sense to. I think Google thinks that way with domain names as well.