That statement can be made regardless of state. I'm pretty sure the costs charged to insurance companies are because of "agreed rates". Sometimes people with shitty insurance negotiate with the provider for the "cash rate". This isn't about the uninsured, it's about the way the system of middle men is setup.
A number of California’s policy decisions, like giving free Medi-Cal to all illegal immigrants and their huge homeless population taking advantage of EMTALA, clearly result in more freeloading on the system. That’s along with California’s consolidation among hospitals, high waste and admin costs, etc.