That's exactly why the inclusion of a hallucinated reference is actually a blessing. Instead going back and forth with the fraudster, just tell them to find the paper. If they can't, case closed. Massive amount of time and money saved.

Isn't telling them to find the paper just "going back and forth with a fraudster"?

One "simple" way of doing this would be to automate it. Have authors step through a lint step when their camera-ready paper is uploaded. Authors would be asked to confirm each reference and link it to a google scholar citation. Maybe the easy references could be auto-populated. Non-public references could be resolved by uploading a signed statement or something.

There's no current way of using this metadata, but it could be nice for future systems.

Even the Scholar team within Google is woefully understaffed.

My gut tells me that it's probably more efficient to just drag authors who do this into some public execution or twitter mob after-the-fact. CVPR does this every so often for authors who submit the same paper to multiple venues. You don't need a lot of samples for deterrence to take effect. That's kind of what this article is doing, in a sense.