If it were illegal to charge a different rate to someone with insurance vs someone without, you would end up with the same result. I'm not sure how you think price negotiation is the problem here. If you have insurance and insurance negotiates a lower price that's at least good for the patient, otherwise the doctor charges the same huge fee to everyone, people with insurance would just have insurance pay what is covered and you're out of pocket for the rest while people without insurance end up paying the entire massive fee.

Negotiations over price is something that is done in every single industry, that's hardly the problem.

I'm not saying that I like this system FYI. I'd much prefer a nationalized health care.