[gojomo]

Even without the ability to trace to an exact purchaser, to be able to correlate multiple documents to the same person, or use the printer as corroborating evidence after finding a suspect by other means, would be very valuable to law enforcement.

And unless the printer is only used for disfavored purposes, its other output is in circulation. Who's to say there's not a ad hoc registry maintained by paper samples culled from filed forms or even trash dumps and recycling bins. ("That serial number was never registered but it was sold from a retail store in Cleveland in 2002 and its printouts were seen in recycling flows in Maryland in 2006.")

[eli]

Uh, I think you're giving the government's tracking and cataloging abilities way too much credit. They have trouble keeping track of a list of terrorists.

It think it's for confirming that a particular printer made a particular note (and determining how many different printers are involved in counterfeiting). Nothing more.