The biggest difference is that social security is a mandated tax and corresponding social program, not the purchase of a service. That may seem like a fine line, but as it is with most taxes the lines are extremely fine and sometimes quite foggy. Medicare is part of the social security program and can be mandated accordingly as a purchase of a service through a government agency as part of the payment received from that agency. To mandate that someone purchase a service from a private or even quasi-private company is not part of what government is supposed to do according to the Constitution. As for the cost of this being a savings, well, let's look at this logically. It is fairly safe to assume that the people who are being added to the insurance rolls are folks with lower incomes. Statistically that is a group that has a much higher percentage of smokers, drinkers, and people with poor health habits and poor diets. In other words, much higher risk individuals. Add to it the increased costs to all healthy insured individuals of people who can not be denied coverage for pre-existing conditions. Again, higher risk and higher cost individuals. This will greatly INCREASE the cost of health insurance, not decrease it. What do you think would happen to your car insurance if your insurance company had to add all really high risk drivers to their pool? Yep, you got it.....or should I say you will get it over and over and over again, and it won't be painless.