You are right that Jesus likes the joyful giver. It is up to every person to give and what he decides to give is between him and God.
In America, we are unique because every citizen has the opportunity to wear two hats. First, everyone is an individual, and we have the ability to donate our time and money as individuals as you have said.
The second hat we put on is as governors of this country. Through our votes, we actually steer the direction our government goes in. Therefore, we have a responsibility to think for ourselves as individuals, but at the same time we have a responsibility to think as stewards of America, because the choices we make at the polls are what shapes this country.
As an individual, I give to charity.
As a voter and an American, I feel I have a responsibility to my fellow Americans. I recognize that as charitable as Americans are, the poor are not getting enough to where they can truly take part in society. Therefore, I think redistribution at a government level in the form of taxes is in the best interest of the country.
The government has the right to tax, it's not stealing. If it were, we wouldn't have been commanded to render unto caesar. The government is supposed to to what is best for the people, by the people. In so doing, we entrust it with the ability to levy taxes.