Medicine was also way less tech-heavy, so the costs were objectively less. Invasive surgeries and similarly advanced treatments are incredibly complex high-tech and high-skill undertakings. If you look at the high end of medicine it's like they're routinely pulling off moon shots: carefully excising brain tumors, separating conjoined twins, transplanting living organs, etc.

I am not suggesting this explains all of it. Our health care system is definitely overpriced and overloaded with badly designed bureaucracy, but it definitely explains some of it.