That's what Google is organizationally unable to understand. They consider you giving them all your data to be a perfectly private thing to do. In fact, in a way, they consider themselves to be sort of guardians of your privacy, since they only look at it themselves and don't let anybody else take advantage of it. To anyone outside Google this not what "privacy" means, of course, but that's the internal mantra.
I don't think they thought this through actually. If I have to pay, I'll pay for Apple iCloud instead, since it has better integration with my devices.