You cannot expect a copy shop clerk, or even manager to interpret copyright law, period.
Actually, I expect anyone who deals with any kind of law to interpret it- I just don't neccessarily expect them to do so properly.
You can expect a company who publishes a .pdf to correctly indicate how someone can use the material in the Copyright Notice
And despite notices even on pre-printed materials- like the aforementioned character sheets- some copy shops ignore the express intent of the IP holder, thus violating the rights of the customer.
Its in solving problems like that that the proposed coding I described (if possible) would be effective, not true mass piracy. If the Kinkos employee loads the PDF onto his equipment for copy and gets a "green light," its copied. If not, Kinko's can't copy the PDF.
No decision making process by someone ill-equipped for the task involved.
Even if the coding solution is not possible, it should be possible for the companies' legal departments to draft a simple decision tree that most people could follow with relative ease...
Perhaps their best overall course would be to chart some kind of middle ground.
For instance, when in doubt, they could make a single copy and note it (and the customer's ID) in a company database. The person in question could then not make another copy of the same IP at any store in their system for X amount of time. The physical copy of the questionable IP could be watermarked.
In the interim, it would be the company's duty to ascertain whether copying the IP again was permissible. If it is, then they clear that data from their records and give the customer a non-watermarked copy.
Would this cause a delay? Sure. OTOH, it does protect IP rights and a legit customer would evenutally get full use of his purchase.
Is this delay a horrible imposition? I don't think so. I have to deal with similar issues when I deposit large checks ($10K+)- the bank has the check, but doesn't let me use all of the money at once. Instead, it releases the funds to my use over time (usually 1-2 weeks).
In comparison, not being able to make multiple copies of a PDF immediately seems trivial.
If it works for banking, a similar system could work for IP protection in the realm of consumer copying.