It shows that the benefit to the people is greater than the pain to the people.
No, it doesn’t say anything about pain to humans. It shows that people collectively consider it worth it. That information is valuable when considering questions like:
Is there any reason why the suffering of factory-farmed animals would be worth it?
No, it doesn’t say anything about pain to humans. It shows that people collectively consider it worth it. That information is valuable when considering questions like: