But why? The way Microsoft, Google, Facebook do it is run the CSAM scans on their server side on everything you upload. Apple could have done that. They could h

But why? The way Microsoft, Google, Facebook do it is run the CSAM scans on their server side on everything you upload. Apple could have done that. They could have done it without announcing anything. They could also have put it on-device as a background service which scanned every photo you took or saved, or every website you visited. Instead they put a non-trivial amount of effort into designing a much more complex system that doesn't require them to be able to see everything you upload, one that has input from multiple countries to guard against a single organization adding meme images to it, one that has an adjustable threshhold for some consideration against false positives, one that doesn't scan everything on your device even though it could do, etc. The actual system was not "really that bad" as you say, considering what it was trying to do, it was a reasonably good attempt to do that. (Not flawless). Apple already send notification of every program you run on macOS back to Apple HQ and sync your browser bookmarks and passwords through them, Google know everything you search for and which results you click and can track you through sites using Google Ads, Microsoft try to get you to send all your browsing traffic to Microsoft and report on executables picked up by Windows Defender. Compared to all these things, Apple's scanner design was tackling a more difficult topic in a more privacy protecting way. I wouldn't be much surprised if Apple push their scanner to macOS as well as iOS, still only for images uploaded to iCloud and not more than that. I would be quite surprised if Microsoft pushed a similar thing Windows 11 and only restricted it to scanning OneDrive uploads; I doubt that the money saved in running the scans on-devices instead of in-datacenter would alone be worth the engineering effort of moving such a system from datacenter to device as Microsoft would have to do, compared to Apple apparently starting from scratch. That is, if it appeared in Windows 11 I'd expect the reason to be being a whole device scanner. I wouldn't be dreadfully surprised if such a system appeared in the Chrome source code and thence to Chromebooks, Chromium and Edge. The next 10 years is probably going to include various pushes from governments and companies into more invasive tech, getting in with a design that is somewhat privacy protecting and setting that as an expectation is not a terrible idea - especially if you assume they don't want to do nothing, or are not allowed to continue doing nothing.