Michael, i like your idea, because i think that liberation of alts from prison could be funny, if there would exist alternative for cash payment. Using skills like traps (C4), steal (to get keys from guards), lockpick,.. in entertaining PVE scenario.
On other way, arguments of previous posters, ecxpet DipullyyyDarf, are valid. I dont want to repeat them, but i have one point. If your idea is proposed as a upgrade or improvement of current TC, then it is wrong, because current TC mechanism is fail, because of many reasons, sadly not only because of bugs.
But your idea of imprison player chars is good and i would like to see it rather in PVE only variation.
My counterproposal:
Everyone knows encouters with raiders, npc faction. So simply: if you are killed in that encouter, you will not respawn in common respawn points, as usual, but you will respawn in prison (cage, locked doors,..) in Raiders base, and your teamates or friends or just hired muscles would have to rescue your char (kill, sneak, lockpick, traps, science skills are required).
And because there are a lot of similar NPC factions on world map (khans, highwaymans,...) a lot of different bases(prisons) could be created, each in different place covering different area, required different skills. So what do you think? It could be first real PVE team mod in the game. Imprisonment has a tradition in Fallout universe (Tandi in Fallout 1, Restoration project quests in F2, Fallout tactics too,...).