Also, it's far from clear that transparency into an AI's algorithms buys you very much. A mathematically inclined college freshman has no trouble understanding

Also, it's far from clear that transparency into an AI's algorithms buys you very much. A mathematically inclined college freshman has no trouble understanding how to train a deep neural network today, but it's at the cutting edge of research to understand what function a trained network is actually computing. Scale that up in complexity a few orders of magnitude, and the thing may as well be a human. That is, you'll likely have broad understanding of its "motives", but we have that for humans today and it doesn't help that much. I understand Facebook wants to sell advertising, but that transparency isn't sufficient for understanding why a particular message is delivered to your followers while another isn't.