Had the experience of poking at tracking dots recently for circumstances I won't share here.
Do y'allself a favor and get a blue LED flashlight and point it at a color print. It's shocking how many are printed. It looks like a spattering of sand across the entire page!
I'm surprised there's not been a class action against printer manufacturers for all the extra yellow toner that's been used.
Not to mention failure to accurately print what you sent to the printer. There must be some use case where these "invisible" dots actually undermine the intended output.
It's not even just for printers anymore.
Not exactly the same thing. This is more akin explosive tracers, i.e., lots of small particles that contain some identifying information.