That's the thing -- they weren't.
The case has two prongs.
One is that training the AI on copyrighted material is somehow infringement, which is total BS and a dangerous path for the world to go down.
The other is that copyrighted material was illegally downloaded by OpenAI, which is pretty much an open and shut case, as they didn't buy up copies of 100k books, they basically torrented them.
And because of ridiculous IP laws bought by industry lobbyists in the dawn of the digital age, the damages are more like $250,000 per book if willful infringement, not $24.95.
Had they purchased them, these cases would very likely be headed for the dumpster heap.
That said, there's a certain irony to Lemmy having pirate subs as one of the most popular while also generally being aggressively pro-enforcement on IP infringement.