Why the big price gaps in hospital bills for surgeries and procedures?

I just saw a news report on tv about the ridiculous price gaps different hospitals charge for surgeries. It was jaw dropping to see such big differences in prices. One man got a bill for $50,000 to have his appendix removed. His insurance would only pay $30,000 which meant he had to come up with rest of the money on his own. Another hospital charged a whopping $182,000 for the same exact procedure. I don’t think hospitals realize most people aren’t millionaires and can’t afford a lot of things. Also, you can’t really get an estimate on how much the surgery will be because no one really knows. I realize it might depend on how long you stay at the hospital to recover and all, but shouldn’t there be some type of regulation on these prices?