The United States Postal Services is a government-run monopoly. As a monopoly, it is the "single" provider of mail service across the nation. Recently, the USPS has for the authority from Congress to substantially raise their prices, and offer less services, reducing their six-day delivery to five-day delivery. What, pay more, get less? That is the nature of how a government-run monopoly operates. Since the USPS actually prevents competition through the force of law, it is a monopoly that isn't the sole provider because individuals have chosen it over other competitors, but rather because it has the power of brute force by preventing its competitors from competing. If any competitor started to deliver first-class mail, the federal government would seize the property of that business and have the courts order an immediate halt to that business.
USPS is a glimpse into the future.
The authoritarian Democrats in Congress want to set up a health care system that would ultimately lead towards a "single payer" government-run health care system. Single "payer" is another way of saying one government-run, authoritarian, top-down bureaucracy that would decide how all health care dollars are spent within the economy. It would be command and control. If you want a certain procedure, the government would have the power to say no to you. Since the government-run health care system would be the only game in town -- hence the name, "single" payer -- you would be stuck.
In a market-economy, individuals decide how much they want of something through the price system. People decide how much of their wealth they are willing to exchange for some good or service. In a government-run system, the price system is eliminated, and the only party that gets to decide how much of a good or service you can receive is the government. This would ultimately mean that there would be an unlimited amount of demand on the system, to the point in which the government would have to use brute force to cut costs by denying patients the ability to get care. This is exactly what we are seeing at the Post Office. Even while the Post Office is preventing individuals from competing with it, it still is determined to cut services and charge customers more. That is why Americans do not want ObamaCare and will vote against Democrats for forcing such a system on the people.