> They decide if the inside of the box is working correctly in an undemocratic fashion, based upon their biases

> Not the correctness of the US judiciary system itself

It's literally their job to do work within the system. The SCotUS is explicitly restricted to interpreting the laws that already exist and were passed by existing legislatures. If you want massive, sweeping changes in the structure and nature of a law, you need to go to the legislature or otherwise pick up rifle and start a revolution. It is not the job of SCotUS to create new law. That's why they get so much flack for "legislating from the bench" when they make sweeping decisions. They're not supposed to do that, and they typically only do when making rulings surrounding the Constitution itself and it's Amendments.