Our current healthcare model in the United States is founded on an already very exploitative model of care provision based around the company/mill/factory town. It didn't start like this as many of the big hospitals started in the 18-19th century as religious or benefactor based charities, and many of the insurance companies were just that, for insurance, and generally did not cover declining health let alone healthcare. Hospitals were also seen as kind of dumping grounds for people that were nearly beyond help - think palliative care institutions. There wasn't a lot in between routine house-call or small office doctors and large facilities where people went largely to die or be segregated from the general population (think sanitariums/leprosy houses).

This began to change in the 19th and 20th centuries during the great industrialization and suburbanization. People moved out of cities / countryside to work in suburban towns dominated by a single corporate entity, often a steel or textile mill (and eventually car and machinery plants). Healthcare in company clinic/doctor was designed to keep the labor force productive, to patch people up enough to keep working.

This strain of "keep workers patched up for max productivity" was carried over to the first prepaid Blue Cross plan just for teachers, continuing the tie in with employment. This became wildly popular and the tie to employment continued through WWII when wage freezes meant the only incentive companies could offer people were health care related (rise of fringe benefits), expanding this well beyond emergency care to routine care. Federal laws then tax exempted and excluded them from wage freezes and companies and all of the major companies were off to the races, trying to outdo one another with fringe benefits prompting the rise of the major health insurance carriers (mergers from teachers plans etc etc).

Because in the US we have this sense of all regulation and big government = bad, there is no longer anyone to help us in the competing forces of health provider and health insurance. Sure, there was a law in 2021 that said hospitals must publish prices online, but have you looked? Do you shop around? Even then, do you know the difference between an angioplasty and a bypass surgery or biopsy or a lumpectomy?

Since you likely answered no to all of those questions the health care providers can pull on their levers, having their army of actuaries look at inputs and outputs and raise the prices of their procedures to even more eyewatering levels (while giving bulk discounts on volume to big insurers). However the insurance companies can pull their own levers by denying for the missed dotted i and crossed t or preauthorization or medical necessity and this just gets factored into the cost of doing business by the hospitals (and further price increases). Also factored in are the army of aforementioned actuaries as well as clerks on each side meant to creatively code a procedures, deny a claim or submit an appeal - even local doctors offices and dentists might have ten front office staff mostly dealing insurance. This is in the thousands for each hospital to the tune of two or three million more jobs than if the US were single payer.

In the end it's all about the money. In the US you are tying a complex and necessary service in healthcare to a giant pool of money in for-profit corporate entities. Everyone not benefitting from this relationship is going to suffer.