A lot of confusion and bad guessing from the rightwingers going on here.
First, the administration positioned this as not being a tax, but being an extension of the Commerce Clause. In reality, that is what it is - and under a less rightwing Court, that is exactly what it would have been decided.
Second, the attorneys for the administration had three points of constitutionality they wanted to argue. The third point was that even if it were a tax - as its detractors claim - then it is still constitutional. That is the point that SC Justice Roberts agreed on. Basically, the administration did a bit of jiu jitsu with the Court: "let's assume you're right about it being a tax. So what? We have the power to tax."
Third, it is not the "largest tax increase in history". People who repeat that are either stupid, or too lazy to look it up -- probably both. The largest tax increase in history using inflation-adjusted dollars, was Reagan's tax increase in 1982. More info here as Politifact shoots down this tired, ragged rightwing urban legend:
http://www.politifact.com/truth-o-meter/statements/2012/jun/28/rush-limbaugh/health-care-law-not-largest-tax-increase-us-histor/
Fourth, in this society, if you are hurt or sick and present yourself for care at a hospital, there is a legal requirement that you receive treatment. But people who don't pay for that treatment are abusing the system. The costs they incur are paid for by the rest of us - in terms of increased healthcare premiums, tax dollars used to pay for their care, etc. To make it worse, people in that situation usually wait until their condition is very far gone and very expensive to fix. They do this, because they are trying to avoid bills they cannot pay. But this is more expensive, instead of dealing with the problem in the early stages when treatment would be far cheaper.
Fifth, this is not a penalty for not doing something, because such people *ARE* doing something. They are acting as free riders in our society, and especially on our healthcare system. That's a deliberate act on their part. And it's a decision that imposes costs on others, in the form of increased taxes and higher insurance premiums, since free riders will receive the benefits but without paying the cost. It's a form of
theft, actually. And it's no different from someone who decides not to pay the renewal fees for the license tabs for their car or truck. Both situations involve a decision *not* to pay for something which equates to a willful decision to become a free rider on some publicly provided service. This is a tax on free riders for their deliberate decision, their deliberate act, to be a free rider in our healthcare system. And I have no problem calling it a tax. Or a ticket.