How is bias built into algorithms? Garbage in, garbage out.

In facial recognition and AI development, computers are trained on massive sets of data, millions of pictures gathered from all over the web. There are only a few publicly available datasets, and a lot of organizations use them. He and Abeba Birhane, at University College Dublin, published a paper recently examining these academic datasets. Most of the pictures are gathered without consent, people can be identified in them and there are racist and pornographic images and text. And even the idea of labeling someone a lawyer or a woman or a criminal based on appearance?