On some printers, this is the reason why the printer will refuse to print a BW-only printout while the only empty cartridge is the color one.

That needs a citation or a sarcasm tag.

Does an anecdote count? My Samsung refuses to print b&w when a color cartridge is empty.

Most likely it tries to print rich black, which uses color to make the b&w printout look better ( and use up all that costly color). You can disable that in your printer settings with most printers.

I heard that before, I think it's a tactic to bully people into buying more ink they don't need. Ensuring tracking dots is maybe just an unfortunate side effect.

I've always assumed that is just lazy design (some resources that _might_ be needed are unavailable, report and refuse to print withut checking if they are actually needed for the current job) rather than due to a security (or even ink selling) measure. I've seen the behaviour as far back as the first colour photocopier I ever used.

I've seen that as well a long time ago on a black+red photocopier, no yellow and probably no tracking patterns since red would have been quite visible.

No, the thing happening does not count as proof why it is happening. Printers refusing to print bw is widely known.

I would also be interested in a citation, but it does make sense; if tracking dots is well known (which they are), and it was easy to circumvent by just removing yellow toner, anyone somewhat technically adept would just remove their toner before printing their illegal documents.

This makes less sense than you might think because the original motivation from the government side was tracing counterfeit currency, not tracking all documents. Printing convincing counterfeit currency without yellow toner would be a challenge!

However, the governments did not succeed in limiting their technology to use in counterfeiting investigations, and may not even have attempted to do so.

If that's true that just makes me angrier because a far better solution would be to improve the currency, like Canada and many other countries did long ago.

I can feel my blood pressure rising...

Imagine the twist this put would on the whole Hanlon's razor thing if this were true.

No idea if this is the real reason, but it's still very annoying.

My previous printer did this, and my current Canon refuses to boot when any cartridge is missing or empty.

My Epson does this, and it's apparently because not having enough ink in the system leads to maintenance issues with heads drying out, etc. Which is understandable, but I wish there was like a 48-hour override so running out of a color didn't prevent me from printing the documents I urgently need RIGHT NOW. So instead, I have to purchase a couple hundred dollars worth of cartridges in advance.

I'm not so sure about that. Having had an inside view into one such program I can say confidently that at least in that particular major manufacturer's situation, that had absolutely nothing to do with it. It was entirely engineering-driven and about preserving the print head.

or so they said... Do you really know the ultimate reason why?

I do, yes. There were sound technical reasons for it.

That doesn't make much sense to me. B/W only (not greyscale) is currently understood to not output these dots at all, so why would the presence of yellow matter?

This is the first thing I thought of when I read about this. It made me quite angry and then a little satisfied finally knowing why this happens.

On the other hand, I didn't think of it until I read this. It made me a little satisfied, and then it made me quite angry.

I ought to be able to do better because I used to know more precisely how many dots per page are printed and how large they are.

But a back-of-the-envelope calculation suggested to me an upper limit of about 1000 kg to 10000 kg of extra toner per year in the United States. However, there are several factors that make me think that even the low figure is an overestimate.

I agree with your frustration about paying for this. Mako Hill used it as an example of an antifeature

https://wiki.mako.cc/Antifeatures

(It might be more accurate to define antifeatures in terms of buyers' willingness to pay to have the features removed, rather than sellers' insistence on being paid to remove them, since we can't, in fact, routinely pay for many of the antifeatures he mentions to be removed.)

Now that you mention it, yellow was the color that ran out first on my printer. By a very large margin.

I mostly print black & white.

But doesn't the comment above yours suggest that the 'yellow' dot thing may no longer be an issue and that now there's variation in the dithering parameters. Suggesting extra ink is not required.

More annoying are the privacy concessions that are the result of secret anti-counterfeiting measures (which is what I assume the measures are for).

I'm pretty sure any kind of such appeal can be refuted by connecting this tracking to hunting terrorists.

Almost none, considering that the dots are nearly invisible, and most of a printed page is visible ink