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Pretty sure it's still Cardboard Prison. That trope includes examples of people being repeatedly bailed out or doors simply being left open and walking out.
Seconding Cardboard Prison as the general one for jail being easy to get out of by any means
Off on a Technicality if they get out via loophole abuse or because of rule-breaking from the judicial side of the courtroom.
Not Proven if they're guilty but get out because there isn't enough conclusive proof that they did it
Bail Equals Freedom for bail being treated as "buy your way out of prison"
Might as Well Not Be in Prison at All if they don't even need to leave to do whatever they want
"Get Out of Jail Free" Card if they have some sort of leverage that gets them out
I could have sworn I saw a trope for this a some point: a work has a prison or judicial system that simply keeps letting anyone arrested out no matter what they're charged with. It's not a Cardboard Prison because the criminals aren't breaking out, instead they're making bail, getting their sentence commuted, getting parole, being stuck with community service, or whatever instead of actually having to stay behind bars no matter what the crime they've committed is.