[Amezarak]

But that's largely the case the article is about: migrant children coming to the US and claiming they're old enough to work these jobs and these hours. You don't have to "somehow" get documents - if a refugee shows up without papers and tells the US government they're 18, how is the US government going to know they're lying? They're issued documents reflecting whatever they said. When the article mentions "dubious" and "fraudulent" documents, this is a major part of what they're talking about. (The other part involves contradictory documentation, and just plain fake IDs.)

"People" will know because they often don't keep it a secret (examples cited in article), and obviously the families know, but auditors and government agencies don't have a way to actually prove it in many cases, unless it's egregious or there's contradictory documentation.