Even for me, with health insurance, one of the reasons I tend not to seek health care is due to the surprise and unpredictable costs. I've already fallen into that trap twice this year alone.
The very first thing I did when I was choosing a plan for this year was filter the list down to the ones I could afford which said they covered all my prescription meds and for which my current health providers were "in-network". That left 2 options.
When I went to get my first round of refills, several months into the year, they said I had to have prior authorization for one of my meds. After going through that process several times, provider who writes the prescription has to jump through the hoops with insurance to get the authorization, the insurance finally came back and said "we don't/won't cover this prescription." My provider was able to find a cheaper, older alternative that works, but I pay out of pocket 100% for it.
Then came my annual physical, which is free with insurance. Because of the meds I'm on, the nurse said they needed to do some blood tests to check for signs of problems. Never mentioned that those tests would cost me extra and obviously I did not know. Wouldn't have mattered, because they wouldn't have been able to tell me up front how much it would cost so that I could make a financial decision about it. In the end, that free annual visit cost me almost $400 that I was not anticipating. The bills started showing up months later, so it completely blindsided me.
Last year was even worse. I had one of the best insurance plans offered through the ACA. Then I had an accident that landed me in the hospital. The ambulance ride was not covered at all, the service was "out-of-network" so I had to pay 100% of that. The 2 tylenol I was given for pain management in the emergency room cost me $40 because insurance would not pay for them without prior authorization. I hesitated to even call for help, hoping I could stop the bleeding myself, because I knew it was going to be an expensive trip to the ER and boy was it ever. Not to mention the follow-up appointments and treatment that was required.