Consider how deep this rabbit hole goes. If expunging any copies of copyrighted data were strictly necessary, then:

What of data existing on backup media? Should those be re-hydrated, the target data expunged, and then recreated in abridged form?

What of data existing in various content caches (such as memcached)? Should all of those systems be flushed of any possible contaminant?

What of the actual data on physical media? Deleting a file on any modern form of media does not expunge the data, it merely unlinks the location of the data on disk from the file system directory. It might be necessary, depending on filesystem and drive type, to scan all of the unused sectors on an entire disk to find out if the target data or any part of it existed.

As you see, quite quickly you get into absurdities. Nobody goes to that much trouble to delete merely copyright infringing data.

I should note that this not true in the case of child porn. Once the feds give them the signal that is completely purged.