Let me give you one example: my friend(and at the time business partner)'s wife got cancer in the US. It was fairly "mundane"/common cancer that got treated and everything was alright at the end. He was working as a software developer (normal employee, not self-employed - our venture was a side project) with the aforementioned "good health insurance" well paid professional middle-class Americans get. At the end of the ordeal he was stuck with a $65k bill (presumably that's just the tip of iceberg and insurance paid more).
Years later I had a malignant tumor here in Germany. Again everything is fine at the end, but it was in many ways a worse case than my friend's wife (due to where the tumor was) & I spent several weeks in a (very nice) hospital in Berlin. I also get an MRI every 6 months to keep track of the situation. I paid a grand total of ~€500 despite being self-employed at the time (so I only had standard public insurance everyone in Germany gets). My twice-yearly MRIs are free. When I was diagnosed with the tumor they offered me an appointment for surgery for 3 days later (I ended up taking it a week later than that as I wanted to get a 2nd opinion).
Neither mine nor my friend's experiences are exceptions.