but I don't think anyone is (seriously) arguing for getting rid of all prisons or fines.
We probably need prisons to some degree, but all fines, and all profit made off of prisons should definitely be stopped. It should legitimately cost the government enough to put a person in prison so as to discourage its use for petty things.
As a constitutional matter, this should immediately extend to things such as having to pay for pretrial monitoring, anger/drug/whatever classes ordered pretrial, and any other conditions other than some sum of money sufficient enough to compel you to return for trial.
Its bad enough we pick the pockets of those on probation as an alternative, but doing it to the innocent (and under the law they are) pretrial is obscene.