They're asking for 5m of their time and a scan of their face, in exchange for 5$. It's a simple transaction, and unlike what the HN-crowd would like to think, the majority of people in the street would quickly make that deal.
The article is putting a lot of their own feelings and opinions on the situation. Just because you have a fear of Google doesn't mean the whole world does, and no one was forced to do anything they didn't want to.
Also, the article mentions homeless people not going to the media (avoiding leaks), not being vulnerable.