Emergency care for things like a heart attack or broken bone only account for 2% of healthcare spending. So your primary case for why "shopping around" is bad is mostly irrelevant. Nothing is stopping you from creating a not-for-profit healthcare co-op, getting participants to voluntarily turn over their healthcare decisions to you, and then demanding reduced prices from vendors. All I ask is that you don't force me to join it against my will.
http://www.politifact.com/truth-o-meter/statements/2013/oct/...