Just as we can't police a society to the extent it's completely free of crime, otherwise we will not function as a society and/or we will find ourselves living in a totalitarian state?
Also, the totalitarian analogy is total nonsense.
Is that correct?
If so, why are you not calling for the internet to be shut down? The collection under discussion is just a subset of the internet.
You'll also want to either ban or enforce review of all camera output, including closed-circuit cameras. Someone is going to have to watch all those watchers pretty closely...
As for totalitarianism, well, how are you going to make any of this happen? As we just saw you'll need client-side visibility into everyone's visual data stores. Not to mention old photo albums world-wide contain images that would set off ImageNet. There are famous paintings and statues that would, too.
[1] Do you exempt NCMEC? If so, how do you justify that?
Get real. Scraped data is going to have problems. The expectation should be that reasonable measures are taken to filter proactively and that reactive measures are taken to remove illicit content found after that.