There is a massive difference between Google for enterprise customers and Google for consumers.
The consumer offering is massively subsidized by ads and will use your data for ad placement, although they still never sell your data because that would hurt their business.
The Enterprise offering guarantees you contractually that they never touch your data.
While I also find it annoying, the alternative of just rolling over and being desensitized to it is much, much worse.
If we're going to be wrong, I'd rather be wrong by being overly cautious than overly trusting.
What do you think their security model will be trained on? That's right, other people's data.
Now, Cloudflare, on the other hand, would be much more likely to offer a service like this.