I think the people who have the capacity to give typically are not sitting with tons of cash in a bank account. Their wealth has been created by either starting a company and building a company or investing in real estate. I could give examples of that.
I'm rather reluctant to talk about my own charity giving, but I've donated, in total, about $25 million to charities. It's all been in the form of stock. If I'd had to pay capital gains tax on gifts when I transferred shares to charities, I would have given a tiny fraction of those amounts in the form of cash.