Apple clearly has very limited ongoing scanning because they report on the order of hundreds of instances of CSAM to NCMEC every year whereas other services with pervasive scanning report on the order of tens of millions of instances.
It’s ok, you are one of the vast majority of people commenting on this topic while reasoning from false premises.
> Then how would they respond to warrants asking for all user identities that upload image x?
Dragnet warrants like this aren’t even legally permissible in the United States, and if they were Apple would obviously reject them. They state that they only provide specific named user account information in response to warrants.