Not that I have much faith in the idea that something being extraordinarily expensive prevents the government from pursuing a particular course, but what you sa

Not that I have much faith in the idea that something being extraordinarily expensive prevents the government from pursuing a particular course, but what you say would cover most cases. But let's say instead of classified documents, we're talking about al-qaeda-training-manual.pdf. One can easily imagine such a document violating federal laws. Say there are various documents the government catches during a raid, on say Bin Laden's compound for example. Say the government would like Google to look around and see who has trafficked in these documents. They don't have to tell Google what the documents are, exactly, just provide hashes/file sizes/ etc. Why wouldn't this happen?