You should care about the Reality Winner case, regardless of what you think about her. Government investigators used printer steganography to bust her for leaking classified information. Here’s how Lifehacker describes it:
Like regular steganography, which is the practice of hiding data (think invisible ink or a watermark on a photo) inside another piece of data, printer steganography uses dots or lines printed throughout the document that correspond to a certain pattern. It’s an invisible watermark that contains metadata like the date and time of printing and the printer used.
So, your privacy is in grave danger, in light of the fact that government agencies, corporations, hackers, private investigators and snoops can positively connect you to the pages that you print via your printer.
Quick Tip: Obfuscation may be your best defense against printer seganography. Protect yourself from preventing the “authorities” from associating you with any particular printer. To do this, consider buying a second-hand printer via an off-grid source (such as a yard sale or thrift shop) that won’t digitally associate you with the transaction. That way, when someone traces your documents, they will lead to someone other than you.
Also, never print sensitive information to a network printer or from a computer that requires you to log-in to print.