I believe the theory goes that the administration expenses incurred by the operation of managing healthcare would be incurred either way, i.e. if the insurance

I believe the theory goes that the administration expenses incurred by the operation of managing healthcare would be incurred either way, i.e. if the insurance companies were not managing distribution of healthcare the government would have to. Given that, allowing the private sector to compete allows capitalist dynamics to drive down the cost. While both government and private companies are both theoretically incented to drive down costs, practically there is a lot more scope for government to operate the plans in an inefficient way without consequence; on the other hand private companies are primarily incentivised by profit, which does not always correlate with the most efficient way of delivering healthcare. This is where the nuance kicks in (i.e. big government or small government); a well run government plan would better but leaning on the private sector is a hedge against poor management.