Nearly 100% of people spend some time in a hospital in their lives.

Unless you're claiming that hospitals only gouge some tiny subset of people and are benevolently generous to everyone else, that number is going to be much closer to 100% than 0.1%.

When I lived in the US, I have personally experienced this, even with top-tier insurance--from both ends: I've had insurance decline claims arbitrarily and pass on five-figure costs to me, and I've had hospitals misclaim things. In both cases, I had to spend dozens of hours on the phone to resolve it.

Most people in the US are far less privileged: Their insurance is not as good, and they don't have the luxury of spending dozens of hours on the phone.

It's just a matter of time until you experience this.