This is exactly what all the anti-Apple people do not get. Google, FB, Dropbox...etc have all been doing this to files stored in the cloud. But I guess thats ok. If they think their files are any safer with another company they have all been duped...lol. Gotta love the anti-Apple crowd...lol.
For the most part and only on shared files. They don't just go willy-nilly scanning ad hoc.
And none of them scan on device. Apple is moving from minimal mail/LEO scanning to invasive forced on device scanning.
Not saying folks should just jump off, but they should do what they feel comfortable with and for those who elect to stay, watch carefully and stay up to date on this.