Actually it's not always supply and demand - only if free market forces are allowed to work.
They work for lazik and plastic surgery because it's not controlled by the government. Then supply and demand prevails.
It was the government that came in and set the price for health care. They reimbursed at a high rate for procedures and at a low rate for visits to primary care physicians. Insurance companies followed suit.
Supply and demand has its effect on plastic surgery but it's having little effect on health care covered by medicare and medicaid.
Supply and demand also prevail because people have a choice about having these procedures. They are luxuries. People won't have them if they aren't affordable. People aren't as picky about price for life-saving treatments.
This is no different than the shortages in gasoline that we saw when prices were fixed back in the early 70's. Some can remember the lines that went around the block simply because there was a rumor that the gas station would get some fuel that day. Nixon thought he could hold prices down with wage and price controls. Well...he did. Prices were low. Only problem was that there was no supply offered at those prices, hence the shortages. The same thing will happen in health care.