‘Overworked, underpaid’ humans train Google’s AI

Can you explain the exploited part?

My understanding is they performed work and were paid for it at market rate. So just regular capitalism. Or was there more to it?

According to the book they kept dropping the rates paid per item forcing people to work ridiculous 12+ hours/day just to get enough to live on, even in the low cost of living places they were in. It was like something in a cyberpunk dystopia but real.

This is a weird sentence, because its got many assumptions baked in that pull the answers in different directions, if they have to conform with the implied definitions you are using.

Global south nations do not have the same level of Judicial recourse, work safety norms, and health infrastructure as does, say, America. So people doing labelling work who then go ahead and kill themselves after getting PTSD, are just costs of doing business.

This can be put under many labels, to transfer the objectionable portion to some other entity or ideology - in your case "capitalism".

That doesn't mean it is actually capitalism. In this case it's exploitating gaps in global legal infrastructure.

I used to bash capitalism happily, but its becoming a white whale, and catch all. We don't even have capitalism anywhere, since you can get far too many definitions for that term today.