The problem is not that the supreme court has never ruled on anything like this, it's that all a supreme court ruling does is to give you something that a good lawyer can refer to in your court case.

Being in the criminal justice system is incredibly expensive and high risk, and as an individual, allowing your case to go to the supreme court requires continually losing it.

A supreme court ruling that doesn't find bails themselves unconstitutional would not help.

If they find bails unconstitutional, then the bail laws are void.

If they only find certain practices wrong, then you need to prove to a court, possibly on appeal, that the conditions from the supreme court judgement hold in your case. So you need a lawyer and some time, post-arraignment... You'll have the joy of having your bail found illegal after 2+ weeks in jail.