That's the only thing I dislike about Jobs. I remember when he gave $300 to a charity a couple of years ago it was a news story because a billionaire was giving $300. That's like a millionaire writing a check for 3 cents.
Personally, I don't see how someone of that wealth could not give back. If you have $6 billion, you could give away $5 billion and still have enough for 100 lifetimes.
I dunno. I think it's surprisingly easy for giving by rich people to go under the radar. Besides asking charities not to publicize their name, it's simply not that easy to get wind of where people give their money and how much they give. For all we know, Jobs could be giving hundreds of $500 checks (like many other billionaires) and we'd never know it.