Google is scrapping information from you from your phone, your browser, your emails, your searches. They track you at scale. They track millions of people at scale! Using all that data + data mining + their AI capabilities + psychologists, they are able to generate incredibly detailed models of each individual. Their models will have predictive power. And that is what their whole business is about - how to best monetise you for their customers and shareholders. (Of course Apple, Facebook, Amazon etc are trying to do the same.)
So, think about it, they have all this information, and will continue to collect it, but won't give you an indication on what they are collecting - why would they do that? Its because we are reaching a data equivalent of the uncanny valley - where google (et al) know you better than you know yourself, but don't want you to know that!
Its a fight for attention! I often do long comments, but sometimes I'm try to get things down to a concise yet witty nugget ;)
So, of course it makes sense that they would like the people whose privacy they are eroding to be in the dark about how much they know about them! Cos then they won't even know to protest! People are already forgetful, if the information is hidden too, in the dark Google et al will have free reign to do what they like.