I've been wondering for a while now why health insurance companies exist at all. They introduce a massive bureaucracy and massive costs and provide very little value. They evolved from a reasonable idea into a monster that just drains our system and do not provide enough value to justify their existence in my opinion.
> They introduce a massive bureaucracy and massive costs and provide very little value. I very much disagree. When I didn't have medical insurance, doctors charged me twice what they charged the insurance companies. Insurance companies have a vested interest in reducing the costs of medical care, while doctors have a vested interest in increasing them. Screwing patients out of payments is not an aligned business mode…
You've identified the symptom but misattributed the cause. You ran afoul of the charge master system of billing, which is a byproduct of our insurance-based healthcare system and the laws which uphold it. In short, providers are "forced" to set their base rates high in the knowledge that insurance companies (their most significant revenue source) will negotiate a fraction of the posted rate. Meanwhile, federal law enforces (under very stiff penalty) that individuals cannot negotiate nor be given a discount from the base rate.
You are also correct to identify the inherent information imbalance in the doctor/patient economic exchange: you as the patient will never know for certain if the recommended course of treatment is appropriate. Realistically only a doctor has enough information to tackle that question. In a cash-based system you are indeed susceptible to abuses.
(In fact, this is one of the main arguments against concierge or "executive" medicine: they will frequently throw in wasteful and dangerous tests like full body scans which have absolutely no justification in medical science.)
But by the same token, insurance company incentives aren't aligned in your interest either, so there are even more abuses on that side.
I believe a single-payer system is the best compromise -- the government's incentives are best aligned to improve the health of the populace (securing a healthy workforce) at the least cost. ("Least cost?!", I can hear the scoffs as I type.) Only government systems have enough scope and lifetime to realize the long-horizon payoffs of preventive healthcare, and cannot so easily escape their failures (the way insurance companies could with lifetime caps). Many people are surprised to learn that Medicare is at least on par in terms of efficiency and above par in terms of patient outcomes and satisfaction.