You say, "C'mon, Williams, nobody's proposing that Congress take over the nation's traffic signals and supermarkets!" You're right, at least for now, but Congress and the president are taking over an area of our lives infinitely more challenging and complex than the management of traffic signals and supermarkets, namely our health care system. Oblivious to the huge information problem in the allocation of resources, the people in Washington have great confidence that they can run our health care system better than we, our physicians and hospitals. Charles Darwin wisely noted more than a century and a half ago that "ignorance more frequently begets confidence than does knowledge." Congress exudes confidence.
Suggesting that Congress and the president are ignorant of the fact that knowledge is highly dispersed and decisions made locally produce the best outcomes might be overly generous. It could be that they know they really don't know what they're doing but just don't give a hoot because it's in their political interest to centralize health care decision-making. Just as one example, how can Congress know whether buying a $4,000 annual health insurance policy would be the best use of healthy 25-year-old Joe Sanders' earnings? Would he be better off purchasing a cheaper catastrophic health insurance policy and saving the rest of the money to put toward a business investment? Politicians really don't care about what Joe thinks is best, because they arrogantly think they know what's best and have the power to coerce.
Hayek said, "The curious task of economics is to illustrate to men how little they really know about what they imagine they can design." We economists have failed miserably in that task.