It's interesting and irritating to look at the Medicare or insurance statement or doc's statement to see what was charged and actually paid. Say 300 for some visit. Doc files that with Medicare or insurance. Medicare or insurance pays 175. Doc's office accepts it. You owe nothing or some trivial amount. If the docs will take something less than the original charge, then why not agree that's what the cost is and be done with it? Maybe people feel like they are getting a good deal by seeing that.
It's kinda like buying stuff at Kohls - You have no idea what it will really cost until checkout.