Now I get it. Sorry for being dense. It's late and I should be getting to bed.
Hmm. What would you do if I told you, Mr. or Ms. Citizen, that your money was suddenly radioactive? Would you wait to get every bill tested, or would you immediately get rid of all the "radioactivity" in your pants, just in case? It's a lot cheaper for them to announce they released hot bills into the economy than to actually do it.
Just a thought.
UV devices do not detect radioactivity. They are probably used to identify special marks on the bills to prevent counterfits. UV's are the "black lights" type of bulb.