Well not to start a new rabbit trail but there are videos of border agents with bags full if ids that were picked up around the river, having been used for transit to the border and then shed so the migrant could start his stay in the USA with a brand new identity.

So I disagree that no id means permanent detention. Not when the hapless BC agent has 100 more in line that day. Better to give the benefit of the doubt and let the hearing in five years figure it out.

The Border Patrol makes them dump almost all of their belongings before entry - which sometimes includes passports and other documentation. This is uniformly bad for the asylees, because they need all that stuff for their various hearings. There's no advantage to the asylee to not having this documentation to "start a brand new identity."

A Honduran showing up with his wife and two kids may be able to get released from detention if he doesn't have his identification. Someone doing their credible fear interview in flawless Guatamalan-inflected Spanish, who can accurately describe conditions in Guatemala and their native village in ways that are consistent with the thousand other Guatemalan interviews that this officer has done, can get released from detention. The Arabic-speaking Yemeni with no ID doesn't fall into that category, and is far more likely to face indefinite detention while the DHS looks into who they really are. Again, it would be dumb to do that instead of just getting on a plane.

theguardian.com - US mexico border agents belongings