20 years ago before there were as many erosions of personal privacy and before I realized how important privacy was, I thought of a similar system to detect counterfeit money.
Scan it and upload the serial to a database. If that serial has been registered somewhere else, before a plane could possibly transport it there, flag both registers to inspect that bill.
If the serial has already been registered as counterfeit, refuse the currency.
If the serial was not issued by the US mint, refuse the currency.
This would have the adverse effect of flagging valid currency too, but this could be worked around. I think it would make counterfeit much harder and have very little technical cost, since reading the denom and serial is trivial.