Correct, and I agree it's an important point, but pre-trial detention is a thing (and I suppose pre-hearing as well)

I think that's how the US justifies it (and I'm certainly not defending the way they do it).

Asylum shouldn't be a "immigrate for free" card. And abusing the system hurts the legitimate claimants more.

Pre-Trial is limited, needs a judge to aprove and is counted against your sentence. Pre-Hearing used to be limited, I'd have to lie on how long exactly, and required a suspected crime to be committed. Something rooted in German history.

Exception, and that got abused often, held in psychiatry in case of imminent risk of self harm and / or harming others.