Differential tax rates (it was once feared) would set class against class. How could they not?
There are the additional problems that state-run efforts to fight poverty morph into efforts against inequality -- and that evidence of their success is spotty -- and that they can even be counter-productive.
And vote-buying is introduced, implicitly or explictly. Professor Adam Lerrick does the math in this morning's WSJ ("Obama and The Tax Tipping Point ... What happens when the majority of voters are net beneficiaries of government?").
What was so revealing about the Joe-the-plumber episode was Joe-the-Senator Biden's scoffing about a plumber worrying about a tax on those making over $250k. What business does he have dreaming? (And he did not even have the state's permission to be a plumber!)