Outsourced, as it often is, to Ezra Klein:
That leaves the United States with the worst of both approaches: Prices aren’t set by the market, but they also aren’t set by the government. Consequently, Medicare’s negotiating power is weakened by the threat that drug companies or hospitals will opt to do business only with higher-paying private insurers. We simultaneously miss out on the efficiency of a purely private system and on the savings of a purely public one.
Read the whole thing.