Waze has turned the nearly undriveable, fifth-steepest hill in America into a disaster-strewn major thoroughfare

I’ll accept that at face value but surely you must admit that there are varying degrees of unsafe. A steep gradient where people have problems stopping is going to be a bit more dangerous than Rodeo between Wilshire and Little Santa Monica Boulevard so let’s not dismiss reports of a road being dangerous simply because other roads have their own dangers.
As to the remainder of your post, I’m not sure what your local governmental problems have to do with the question of whether to address the dangerous road or the application that may route people on to that road. If your local government is too dysfunctional to act in order to provide a safer and better environment for its citizens, then that’s an issue to be addressed separately and does not speak to the question of what choice would be best when dealing with an unsafe public road.