I don’t think they need 15000 IRS goons to collect a penalty.
Under Obamacare the 15000 new IRS agents do a lot more than collect the penalty.
And the payment that you have to make only if you fail to comply with a government mandate is in fact a penalty. Prior to Obamacare, there was a long line of cases defining “Tax” and a selective penalty only applied to those who do not comply doesn’t fit the definition.
However, whether or not it is a tax or a penalty, the process by which it can transform a federal government dictate to participate in interstate commerce into something constitutional is still a mystery.