This situation reminds me of how they would only medically study male bodies and assumed everything would be applicable to women.
There's also a problem with facial recognition and darker skin pigment. I mean, why not throw a couple black people in the study groups!? Maybe then we wouldn't have all these issues...
The amount of melanin in one's skin is irrelevant in any sort of sense other than very real medical applications. Another area is tatoo removal lasers which won't harm white/lighter skin, but will damage people with darker skin pigment. It can cause both hyperpigmentaion and hypopigmentation as well as keloid scars in individuals with higher levels of melanin. (There are specialized tattoo removal lasers available for darker skin pigments.)
I remember a mini-controversy of home tattoo removal lasers (sounds like a bad idea in general to me!) that offered no warning to potential users that they could damage their skin depending on how dark their skin pigment is.
It just seems to me that there's an implicit discrimination in the populations used for studies. You'd think it would be obvious to try to represent each of the six skin shades on the Fitzpatrick scale with multiple participants if you're studying or developing technology related to our skin...
Edit: Smart watches that use lasers for the health measures are flawed as well. Again, that makes me think that people of color were clearly underrepresented in the studies developing this tech.