Vox suggests that the government can't just release Central American asylum seekers from CBP detention, because they could end up lost and confused on the streets. But I'm not sure that's a good enough reason to keep people detained. https://www.vox.com/2019/4/11/18290677/border-immigration-illegal-asylum-central-america-mexico-trump
The border is in crisis. Here’s how it got this bad.

There really is something unprecedented — and deadly — happening at the US-Mexico border right now. But the threat is to migrants themselves.