Apple could have saved themselves so much backlash and not have caused the outrage to be focused exclusively on them if they hadn't tried to be novel with their method of hashing, and had just announced that they were about to do exactly what all the other tech companies had already been doing for years - server side scanning.
Apple would still be accused of walking back on its claims of protecting users' privacy, but for a different reason - by trying to conform. Instead of wasting all the debate on how Apple and only Apple is violating everyone's privacy with its on-device scanning mechanism, which was without precedent, this could have been an educational experience for many people about how little privacy is valued in the cloud in general, no matter who you choose to give your data to, because there is precedent for such privacy violations that take place on the server.
Apple could have been just one of the companies in a long line of others whose data management policies would have received significant renewed attention as a result of this. Instead, everyone is focused on criticizing Apple.
There is a significant problem with people's perception of "privacy" in tech if merely moving the scan on-device causes this much backlash while those same people stayed silent during the times that Google and Facebook and the rest adopted the very same technique on the server in the past decade. Maybe if Apple had done the same, they would have been able to get away with it.
This is my understanding too. But is this not also true for other (cloud-based) CSAM scanning systems? Why is Apple's special in this regard?