The problem is the the overwhelming majority of Americans don't know this. I've had this conversation with many people and almost all don't know that you can get your cost discounted and that you can usually get them discounted to the Medicare/Medicaid price (which you just need to discover by matching it to CPT codes).
My mom was told about a procedure that would have cost her $120k, in one question the price dropped to $30k. That's such an unfathomable discount that I think many people are ignorant because it sounds too good to be true. They end up thinking that it doesn't exist, there is some catch or that they probably don't qualify somehow.
Fwiw, I've asked this at two locations, mostly for curiosity's sake. In both cases, the cash price was about 50% higher than what would have been paid through insurance, which was 100% not covered by my insurance.
Their reason was that insurance companies usually pay a predictable amount, but people paying cash frequently stop paying and get punted to collection agencies, ending up with (significantly) less money actually going to the hospital.