> If your phone began analyzing your local photos for child porn, you'd probably be upset, no?

Yep. "local" here is the key word, though. If a service I uploaded photos to began doing that, I would not be upset. And indeed, just about every image-hosting website in existence already does this, because they're legally required to.

Gmail is markedly not a local service.

> True, but google is CURRENTLY abusing it by selling ads to me based on it.

This makes it seem like your concern is with the advertisement funding model, not with privacy.