And here's a thought - we should align the tax benefits for charitable giving with the amount of money that actually goes to charity. For example, the full corpus of an endowment is exempt from taxes, even though most foundations only spend a small percentage (around 5%) of their endowment earnings on charitable purposes. So the actual tax benefit ought to align with the charitable dollars - the 5% given in grants, not the 100% of the endowment which is in market rate investment vehicles.
If endowment managers can demonstrate alignment between their investment policies and their charitable missions, then the tax benefit would be extended to those investments. If a foundation invests 10% of its corpus in companies that serve a public benefit purpose in line with the foundation's mission, then the tax exemption would extend to include the 5% it pays in grants and the 10% of its endowment that it is using to achieve its mission. The other 90% of the endowment would be taxed.
After all, why are taxpayers subsidizing market-rate investment capital? Shouldn't public benefit tax exemptions be granted for public benefit activities?