I'm unemployed and without insurance. If I go to the dentist's office to get a small no-anesthesia filling, as I did last week, they will accept $116 from an insurance company but will charge me $167 for exactly the same procedure because I'm a cash payer. When an insurance company pays them, they deduct the difference between $167 and $116 as a "loss" to reduce their taxes.
Paper losses like this are not tax deductible. I work with a medical office, and that is one of the first tax-related truths they discovered.
On the other hand, taking advantage of people is unfortunately part of human nature. The nice part about paying cash is you can say, "I will pay you in full now. If you bill the insurance company, you have to submit a claim and pray that they pay and not recoup the payment in the future. And, please give me your best price now because I am going to three of your competitors who are conveniently located in this same neighborhood and will ask them their best price. Then I will choose, and I won't be back if your office is not the winner."
This is called capitalism: make it work for you!