Multiple studies have shown that facial recognition works poorly on 'people of color' generally. Might be related to calibration, but probably is related to poor contrast - like the early film industry's migration from brunettes and towards blondes.
Naw. Obviously the machines are racist. /sarc
That’s because dark people are dark - facial recognition breaks your face down into a matrix, and uses certain functions that give another matrix of changes in brightness / color as you go across the image. (Like how an acceleration graph is a derivation of speed over time, and speed is a derivation of distance over time.) Dark people don’t have much shadow as you go across the face, the skin is already dark so it’s difficult to establish markers to make those comparisons with.