Sometimes humans workers are the artificial intelligence. Behind FB content moderating AI are thousands of content moderators. Behind Alexa is a global team of transcribers, and behind Google Duplex are (sometimes) very human callers mimicking the AI that mimics humans.
Artificial intelligence doesn’t run on magic pixie dust. It runs on invisible laborers who train algorithms relentlessly, until they have automated their jobs away.

Because they don’t know each other they are unable to demand good working conditions. And because society doesn’t know about them, there’s no accountability.