Just a joke about the power of the presidency. Made by Jay Leno it might have been funny. But as told by Mr. Obama, the actual president of the United States, it's hard to see the humor. Surely he's aware that other presidents, most notably Richard Nixon, have abused the power of the Internal Revenue Service to harass their political opponents. But that abuse generated a powerful backlash and with good reason. Should the IRS come to be seen as just a bunch of enforcers for whoever is in political power, the result would be an enormous loss of legitimacy for the tax system.
Our income-tax system is based on voluntary compliance and honest reporting by citizens. It couldn't possibly function if most people decided to cheat. Sure, the system is backed up by the dreaded IRS audit. But the threat is, while not exactly hollow, limited: The IRS can't audit more than a tiny fraction of taxpayers. If Americans started acting like Italians, who famously see tax evasion as a national pastime, the system would collapse.