Lots of people think we should raise taxes but then don't extend this to donating to the government. If you think you should be required to pay more in taxes, why don't you do it voluntarily? It's not a prisoner's dillema problem: the government can do good things with your money even if other people don't voluntarily increase their taxes. One phrasing of this is "why is the government's share of the voluntary donation market so small?"
My voluntary donations go to the charity that I think is best, which isn't the government. But the government may still be, in my opinion, a much better charity than the ones other people are giving to. The amount of extra good the government can do with more money outweighs the small amount of money I wouldn't be able to give away because of my personal tax increase, even when considering other people's decreased discretionary money. (I would prefer a tax to benefit GiveWell's top charity, but that's not going to happen.)