Those with money pay too much for insurance because those without insurance are only covered at the last stages, when it becomes inhumane (by anyone's definition) to deny them care (which is also the most drastic and expensive level of care for a problem) which is then 'written off' and padded in to the 'prices' asked for other services.
A LOT of medical costs are actually sunk fixed op-ex. Big expensive machines that cost deferentially little to use or not (but always coast a lot to have the option of using), drugs and other supplies that have shelf lifes, etc.
Labwork presently requires a lot of humans, but much of it could also be converted to automation and human review, lowering the per unit cost; if there were incentive to make such technology.
It's also a major bit of administrative overhead to have to haggle with different insurance companies, hound patients for billing, and in general worry IF someone will pay and how much.