The Truth lives just North of The Bottom Line and just West of Survival, on the opposite side of the Situational Ethics Building... or was that The Question? I always get those somewhat obscure heroes mixed up.
I suspect their uploading or in any way observing just what you're reading, beyond the normal accounting of what books are bought from them, would be a gross violation of established privacy laws, not to mention a corporate suicide... then again, anything is possible and if they only maintained a general count of what is being read by how many people and made no attempt to associate that count with anyone's identity why would most people care? Similar marketing data is collected every day -likely more often than any of us realize. Better to assume there is no such thing as privacy and plan accordingly... say registering your device as belonging to whatever government figure has annoyed you the most before you download that Fifty Shades stuff.