The problem is that Apple cannot actually see the image at its original resolution because of the supposed liability of harboring CSAM, but being able to retrie

The problem is that Apple cannot actually see the image at its original resolution because of the supposed liability of harboring CSAM, but being able to retrieve the original image would mean being able to know the complete contents of the rest of its data. To me, it sounds like Apple is trying to make a compromise between having as little knowledge of data on the server as possible and remaining in compliance with the law, but that compromise is impractical to execute. The law states that if you find an image that's believed to be CSAM, you must report it to the authorities. If Apple's model detects CSAM on the device, sending the whole image to the moderation system for false positives carries the risk of breaking the law, because the images are likely going to be known CSAM, since that's what the database is intended to detect, so they'd be accused of storing it knowingly. Perhaps that's why the thumbnail system is needed. So why wouldn't Apple store the files unencrypted and scan them when they arrive? That would mean Apple would remove themselves from liability by preventing themselves from gaining knowledge of which images are CSAM or not until they're scanned for, but could still send the original copy of the image with a far lower chance of false positives when something is found. That knowledge or the lack of it about the nature of the image is the crucial factor, and once they believe an image is CSAM they cannot ignore it or stop believing it's CSAM later. That question may hold the answer to why Apple attempted to innovate in how it scans for child abuse material, perhaps to a fault.