You just answered it? One is a ML system and one is a human?
I'm really, really baffled why people keep using this argument. Like you guys know machines are not humans, right? ...right?
Humans are special cases in laws. Always have been and always will be (until AGI). A pedestrian is treated differently in laws than a driver is. The fact that a pair of legs and a car both move you from point A to point B doesn't make them same. Selling human livers on your local market is very different from selling cow livers, even biologically they are all organic tissues.
Let me say it again: humans are special cases. AI learning copyrighted materials might be illegal or legal, but it has little to do with "what if a human being does the same".