The way you decide whether to trust someone or something is whether someone you already trust trust them. So the question is: who do you trust and how far does your chain of trust go?
For me, I need to trust my coworkers. And I do. And I trust that those coworkers will report misbehavior internally such that I can see it.
And from what I know, I trust them to look after my data. They have everything: search history, location history, email, photos of my daughter. I am not a product. I am a leaf on a human-indecipherable neural net that shows me a particular ad.
Companies don't care about people. Companies aren't people. People care about people. I do not think Google The Company "wants" anything in any way you can moralize good or bad. Google The People want to do right by users.
So, the question is, do you trust me? :)