That's a good question. The ML bias this isn't necessarily due to one prejudiced person doing this on purpose. It's connected to systemic racism where history and culture added up to the status quo that is biased.
The fact is that training sets usually contain many more white men than black women, especially if they're just scraped off the web. People who guided the training may have just used datasets that reflect their own culture and demographics of their own country, and didn't see a problem with that. The opposite would have been be seen as "pandering to diversity" in their country, so they've ended up with a biased dataset and a biased algorithm.
The fact is that training sets usually contain many more white men than black women, especially if they're just scraped off the web. People who guided the training may have just used datasets that reflect their own culture and demographics of their own country, and didn't see a problem with that. The opposite would have been be seen as "pandering to diversity" in their country, so they've ended up with a biased dataset and a biased algorithm.