Google and Microsoft have been scanning everything in your account against a hash database for the past decade.
Also, unlike Apple's system which doesn't even notify Apple of the first 30 positive results (to protect you from the inevitable false positives) Google and Microsoft offer users no such protection.
>then they notify law enforcement if they get a hit. Which means even if you're innocent - all your devices get confiscated for months, you probably rack up tens of thousands of dollars in legal fees, maybe lose your job, probably lose your friends and get the boot from any social organizations or groups.
Again, Google and Microsoft have already been doing this for the past decade.
>a man [was] arrested on child pornography charges, after Google tipped off authorities about illegal images found in the Houston suspect's Gmail account
https://techcrunch.com/2014/08/06/why-the-gmail-scan-that-le...