It's more complicated than that. Only 2 or 3 images are meant to train AI, the rest are meant to establish whether you're human enough that AI can learn from you.
I think the actual website detection is usually done that way, while the AI training is generally separate and runs it's own standalone game.
It's all a ranking system. Who knows the score - my goal is to get through in as dishonest a way as possible. If they want my honest answers they should pay me for them.