Thanks to Google's indifference, the pirates can continue to sell ebooks no matter how many times copyright holders might complain. If Google takes a pirated ebook down in response to a DMCA notice, the pirates simply upload another copy of the same title.
If you pirates to stop distributing your works, you need to go after the pirates. Google is not your mommy. It won't kiss you and make everything all right.
DMCA requires platforms to take down very specifically identified infringements. The same work uploaded by another user is not necessarily an infringement, so another notification is required on behalf of the rights owner. Not policing for infringement is not a sign of indifference on the behalf of the platform. Policing is not required of the platform because it is impossible for it to do so.