He, and others, use this tactic to show how magnanimous and selfless they are. Of course, it is complete and utter nonsense. It is pure demagoguery and absolutely dishonest. It is the height of disingenuousness.
If Mr. Kristof wants to pay more taxes, no government action is required. The Treasury Department accepts donations. Kristof knows this.
What he really means is that he wants the government to raise YOUR taxes.
Of course, this is yet another example of the language of statists, Newspeak: Say something that you do not mean to achieve a hidden purpose. War is peace, night is day. Your money is my money.