Last year my sister had suregery to remove a growth on her wrist. She dosent have any insurance so I picked up the bill for her (Long story she needs my help and better me than the Government). When the Doctor and the Anethsiologist found out I was paying cash they both cut their fees by 2/3's because they didnt have to deal with insurance. That explains it right there.
But when my sister in law was out of work and had no insurance, she encountered people who would not treat her at all, when she offered to pay out of pocket.
I suspect it was because they no longer had a blank-check opportunity to loot and plunder her coverage.
Yet, I know several physicians personally who walked away from their practices because they could no longer stand dealing with HMO paperwork.
Maybe some providers are better at gaming the system than others.
You were lucky. Because of contracts with HMO's and PPO's etc, many physicians and hospitals are not allowed to charge less than full price to those not covered by insurance. The HMO's and PPO's etc have negotiated deep discounts from list price. I think you will find that hospitals in particular will charge those without insurance say 50% more than what someone with insurance would pay for the same service regardless of whether they have to jump through hoops to get payment.