This is simply because film equipment materials and processes have also been optimized for lighter skin. It isn't a problem with dark skin, it's a problem with photography as an industry systematically privileging better results for lighter skin, and even defining paleness as "normal".
There are:
1) technical limitations - even high end color printers today, have problems with reproducing various shades of brown, which is what almost all Black people in the USA at least, are (there are a few people with very dark skin which is more truly black).
If you want a torture test for a color printer, take a photo of a brown/beige wall with a medium brown sofa in front of it, lit by a single light source from one side. The range of brown colors will be very tough to produce properly.
2) tuning limitations, often of the photographer - you can look at black and white photos from even the 1940s for instance of musicians and the black musicians are exposed and developed properly. See for instance the first photo here: https://unblinkingeye.com/Articles/Harvey/harvey.html or an image search for "1940s jazz musicians"
The school photographer that the person mentioned in the article just didn't know how to adjust the exposure properly; they likely set up a distance from the camera, with a set amount of flash, set the same exposure for that school like they did for the 20 others they were going to, and popped off all the photos at the exact same settings.
Whenever you see an article about someone complaining about "privileged photographic chemical processes" -- check to see if the author of the article ever talked to an actual color scientist.
Note: there are some changes in the chemistry to allow for tinting - but that is a bias that can be overcome quite easily if photographing people who are of a different ethnicity.
I am not a color scientist, but I am a photo- and videographer and have done print design and I've had reason to stare into video codecs in the past, so while I'm not an expert and would not claim to be one, I have some familiarity with digital and paper color reproduction.
You are, to be 100% clear, correct about this in the current state of the world. But it's also quite easy for this to be a just-so story: printers are bad at this, sure, but I'm aware of no reason that they have to be.
Analogies are always suspect, but consider: 15-bit RGB color is noticeably less able to articulate perceptual green gradients, which is why a common color format is thus 565--that's optimizing for human biology. We sell monitors to humans, not to dogs. Now, take it back to film and to paper: is a roll of film or a printer dealing with hard limits of physics or biology, or just optimizing for the assumption that the people guiding the research, specifying product output, and (for a long time) buying that output...had lighter skin?
It doesn't have to be a conspiracy. It can just be the local maximum of capitalism.txt leading to worse global outcomes.
From https://www.canva.com/colors/color-meanings/brown/ :
"In a RGB color space (made from three colored lights for red, green, and blue), hex #964B00 is made of 58.8% red, 29.4% green and 0% blue. In a CMYK color space (also known as process color, or four color, and used in color printing), hex #964B00 is made of 0% cyan, 50% magenta, 100% yellow and 41% black. Brown has a hue angle of 30 degrees, a saturation of 100% and a lightness of 29.4%." (of course different browns will vary)
Since the mixing requires magenta, yellow and black, it is just that much more difficult to get it exactly correct.
If the world had used something other than CMYK, perhaps it would be easier - but it would likely still be a tertiary color which requires very careful quality control; and as you no doubt remember, early color printers suffered from "metamerism" where the perceived color/intensity would vary depending on the angle of the light hitting the ink on the paper, or the angle at which the paper was viewed.
Btw this is exactly the same reason why camera lenses are black on the inside.
No "if" about it - your hypothetical translored. Kodak only got better at capturing darker browns after chocolate and Furniture industries (lots of wood hues) complained about not being able to get good pictures quality of their products.
A team of two unlikely businesses—furniture makers and chocolate manufacturers—protested against Kodak’s films for discriminating against dark hues[1]
My point is that any new visual technology will have problems capturing detail of black any objects. Vintage film didn't capture black detail because information is lost because the object destroyed it.
Btw, the problem still exists. Kodak didnt magically conjure a product with ten more stops of dynamic range. Maybe a stop or two and lot of heuristics. Grab the fanciest camera you can and try taking a picture of an object painted with vantablack. It is impossible.
Likewise, I have zero surprise that ppl with dark skin trip up vision systems that have been widely deployed for only ten years. That is not evidence of researcher bias; its evidence that its a new technology trying to get something to work. If this issue is ignored for next 90, than we can conclude that there is bias.
So what to so until then? Just let black people be victimized? NO! How about we throw away our techno-dystopian state and its abominable technology instead?