Politicians make lots of money when they leave office — witness the tens of millions the Clintons have made, and the tens of millions Paul Ryan will make. Politicians are no more ethical than businessmen, and they are not more benevolent. When politicians decide which treatments will be covered, and which will not be covered, and who gets licensed to supply those treatments, they’ll decide based on the recommendations of highly paid lobbyists and donors. And when they leave office they’ll become lobbyists in turn.
Waste makes a business vulnerable to competitors; Waste is the lifeblood of the government/rent-seeker economy.
Again, I think it’s fair to argue that a fully public system, or a single payer system might distribute resources more fairly. But it cannot be more efficient.