>Those who do not get access to healthcare services and die will not be able to vote with their wallets. They are gone.
While I agree with most of what you said, if the insurance company lets a person die, then that person no longer pays them for insurance and never will again - essentially "voting with their wallet", even if not directly. While that may be an insignificant amount of money to the insurance company, if their policies led to many people not getting the treatment they needed, the people would either die or seek other insurance, and either way stop paying the company for insurance. Though this can be problematic if the insurance is supplied by an employer, as they don't always offer a choice of insurance companies.
But the real problem with the US medical system is the medical treatments costing far, far far more than is reasonable. In other countries medical care costs are way more reasonable. People don't get bankrupted by medical expenses. And there's too many stories out there about hospitals and doctors billing insurance ridiculously high costs, and if the bill isn't being paid by insurance companies then the price is lowered substantially.
It's a fucked up system, through and through. Many/most hospitals are for-profit ventures, and they really do try to extract the most money that they can, however they can get it - and that usually means sending a ridiculously high bill to the insurance company and then insurance tries to negotiate it down. A routine operation should not cost over $100,000, but that is often what the insurance company gets billed.