Imo this is just good old fashioned quality control. When you can't trust your wholesaler you randomly sample the shipment and test it, rejecting the whole shipment (or exact penalties) for product outside an acceptable threshold.

The publisher could supply a manuscript. It could be compared against the manuscript database (note: not with a checksum), and if it's too similar to other copyrighted works then it should flagged for manual review, and rejected if identical. That way you leave the door open for new translations/editions from different publishers, which should be treated as separate products.

Then when the shipment of physical books arrive, you sample them via OCR + text differences and if it's outside your standards, reject it.

But like the article mentions, that's expensive.