Numerous brands of color laser printers leave coded metadata in barely perceptible yellow dots that can be used to trace a printed document to its source, a feature originally intended as a deterrent to counterfeiting currency with laser printers.
What's Undetermined
While a majority of laser printers are designed to produce this secret metadata, it is unclear exactly how many printing companies and models employ the technology.
You can legally copy US currency in black and white because, like you suggested, it's obviously not real. So if that's the reason for the micro printing it wouldn't be applicable on a black only laser printer. The original post is also not relevant to your situation at all anyway...
Nothing beats my old black and white laser printer that accepts 10 dollar third party cartridges! Never dries out and prints thousands of pages on a cartridge.
i had an old-ass dot matrix, tractor feed printer in the 2000s that decided one day to only print a few smiley faces when i needed to print a college paper. some dickhead got a laugh out of designing that in like 1989.
After the last Canon inkjet printer clogged up, just like the last one did, and the one before it, I just got a small Laserjet monochrome to see if I can beat the system.
Iirc even when printing black-and-white and specifically not choosing to print in color, the printer still uses some of the other colors to get a more “true” black. So in order to legit print in just black-and-white, you want a monochrome printer - otherwise, the printer will keep using smaller amounts of other ink for the black colors.
You're close. True black, like black text, will use black only. But any slightly off shade of black will combine all other colors to make some kind of grey because if you're using a color printer grey isn't just "less black". You can fix this by either setting your color printer to black only or grayscale, or like you said getting a monochromatic laser printer.
Um, what? Black is the darkest color. Technically the absence of all colors. You're not going to get a darker black by mixing cyan. In fact it will probably get lighter.