Let's say the training dataset has the same proportion of black people as their proportion of the population. That, by itself would be biased for the ML, since

Let's say the training dataset has the same proportion of black people as their proportion of the population. That, by itself would be biased for the ML, since there are fewer images. But it's not an indication of bias by the people programming it. But this would imply you need huge data-sets for every minority, not matter how small a proportion of the population. It might instead be necessary to teach the model about race as a concept, so it can categorize images, and then process them correctly. But of course that leads to a different can of worms since you are explicitly making a "race aware" ML.