My views come from years of working in government and politics, following current events, and reading inside accounts of how the political system works. Probably the best book on getting an understanding of how government works in practice is "Government's End" by Jonathan Rauch. If you want a more entertaining view, watch a few episodes of "Yes, Minister", which was based on the diaries of British cabinet minister Richard Crossman. Or simply take the time to learn in depth the politics and policy of one particular area, such as education. For example, the other day I was talking to a mayoral candidate in Boston. He explained that the biggest factor blocking all of the major reforms he would like to do were the teacher unions, and that they are extremely powerful because they vote as a block in a way that promotes their own interests.
The difference between government charity and private charity is that the workers in government charities form voting blocks that can redirect government tax payer dollars to fund their pay. Private charities must convince donors to voluntarily donate money.
I want to elaborate on your last sentence. With private charities I have much more direct influence on how my income is used. If a charity I am donating to no longer serves purposes with which I agree I am free to stop donating. Try to stop paying the government for programs which you don't support or strongly object to.
The difference between government charity and private charity is that the workers in government charities form voting blocks that can redirect government tax payer dollars to fund their pay. Private charities must convince donors to voluntarily donate money.