Earlier quoted context omitted.
Your understanding is correct, as was/is the understanding of people critical of the feature. People simply don't want their device's default state to be "silently working against you, unless you are hyperaware of everything that needs to be disabled". Attacks on this desire were felt particularly strongly due to Apple having no legal requirement to implement that functionality. One also can't make the moral argument…
> People simply don't want their device's default state to be "silently working against you That was the misconception of what was happening though. Nothing happens on your device. Only when it gets to the cloud. It just puts a flag on the picture in question to have the cloud scan it. Which is exactly what happens before Apple suggested it and happens now. Except it does it for all your files. > One also can't make…
Your phone is your most trusted agent-- it's a mandatory part of your life that mediates your interactions with friends, family, lovers, the government, your doctors, your lawyers, and your priest. You share with it secrets you would tell no other person. It's always with you, tracking your location and recording your activities. And in many cases its use is practically mandated. I think it's inappropriate for such a device to serve any interest except your own.
While it is true that the original proposal operated only on images that you would upload to icloud many people assumed the functionality would be applied more widely over time. This article seems to have proved that point: Apple is now applying essentially the same scanning technology (this time they claim the databases is of "landmarks") to otherwise entirely local photos.