Interesting detail to focus on. Would not have occurred to me anyway.

Is there a more accurate but still commonly used word that most english speakers would understanding as roughly grouping people by the shade of their skin?

Also is it possible that it does break down across the same lines we'd draw for "race?" For example I have pretty dark skin for my national origin, am usually, but not always, considered white at first glance. There are certainly black people with skin as light as mine, but our "tones" are usually quite different. It's not absurd to me that details like that could affect sensors like this.