You forget that taxes tend to penalize a part of the population, be it progressive, regressive, or proportionate. But charity is not an imposition. People who can and are willing to pay, feel absolutely free to do so. Now, how many of them are willing... still remains to be checked.
LOL, rich people steal in a civilized manner? They also kill in a 'civilized' manner. Then, they are 'civilized' criminals. 
Then, we must be having a 'civilized' court to judge them, 'civilized' prisons to keep them in, and if their crime is heinous, a 'civilized' death? LOL, seriously Borakk? 
And about the "give what you need". A simple example. You have kept some yogurt in the fridge. It got spoiled, meaning you don't need it anymore. So, you will give away the yogurt YOU can't eat to someone poor, just because throwing it away is a waste??
And you tend to forget the focus of this topic. This topic focuses on
whether taxes and charity are equal or not!. Not the system or method of taxes or charity.
Charity is voluntary, but most people pay it just cause their religion tells them to or just to show people. So, its not actually voluntary, just like taxes. And if the fact that "Taxes = Charity" is publicized by the government through various promotion medias extensively, people will be more willing to pay taxes, some will even pay it voluntarily. They will avoid charity, whose purpose is served by taxes. If people can make the purpose of charity serve in taxes, why pay taxes and charity
separately and waste money?
Yes. It is much better and honourable to steal in a civilized manner. I
strongly believe that stealing is not bad, but it must be done in a civilized and honourable way.
And the value of charity is
deemed by the person who receives it. If a rich person has a plate of rice, which is one day old and a little stale, it is of very little value to him because he can easily cook another plate of rice or buy them. But to a poor people, this one plate of rice (be it stale), is of
very high real value because he is after all, tensed whether he will get his next meal or not. It is
very pleasing for him to know that he is able to get his next meal (doesn't matter to him if it is stale), without being tensed or working hard for it. So, even if we give poor people what we don't need, it is of a very high
real value to them. And as long as this serves true, your equation of "give what you need" doesn't hold true. The "give what you don't need" formula is true.
