Pulse oximeters give biased results for people with darker skin

I get that it is interesting to research optically measuring systems to 'search for bias' and I'm sure there are going to be biases in varying degrees, but that doesn't mean it's always for the same reason or with the same result.

There are very real problems of course, take the example with the photographic film development from the article: that is a problem because a picture that is supposed to reflect the subject you photographed no longer does what it was suppsoed to do. And someone here posted the example of the soap dispenser that couldn't "see" people that didn't have light skin. Also a problem, because now you can't get soap. Both of those are mostly examples of errors made during engineering (apply Hanlon's razor when in doubt - it's not always malice like people often assume), and might be preventable if there were more different samples and interactions available during development.

That doesn't mean it's the only type of problem we have with devices for humans, or that keeping a color palette of people around is always going to fix it.

Take the soap dispenser example: you could have made one that uses radar or ultrasonic detection, solves multiple problems because you now don't have to consider lighting conditions which always vary due to differences in bathrooms (light fixtures, positioning, positioning of the dispenser itself etc). That doesn't relate to skin color, but can just as easily be a similar problem that could have been prevented all the same by doing proper engineering. But it's likely that in cases like this (soap dispensers) the detection system was just a module that some other third party company imports and sells, and they bought it from a module integrator somewhere else and they bought the parts as generic motion detectors from a company 4 layers down the chain that specializes in measuring daytime movements of rabbits or something silly like that.

On the other hand: if you have a government that requires certain controls to be in place and applied for medical equipment to be used in a medical setting you would expect some of the requirements to be drawn up in a way that reflects the use cases. It appears that either the devices are not scoped within those controls, or the controls failed. Or it's all good and the difference in measurement is not significant enough to matter for the use case and thus the devices are used as-is and this research doesn't relate to the real world as well as people think.

For one, according to the article the discrepancy was found to be up to 8 points in some cases, not 3. And it seems reasonable that quick, practical decisions in hospitals are made based on point thresholds, not purely huge point leaps as you suggest.

I haven't dug any further than the article and your comment to verify these facts. But rather than find a way to prove why this doesn't matter, why don't we assume it does? Then the knowledge and awareness might spread a little bit more through us, and if it is an issue, it might be that much more likely to be solved. There's no penalty for being wrong with a weakly held but well-meaning assumption. At the very least, we can be more aware of another possible dimension of bias in technology.