Speaking for U.S. tax law only, there is something called an "in-kind contribution of professional services." This allows people with particular skills to perform a service (design, coding, carpentry, etc.) for a registered not-for-profit, receive a letter from the NFP stating the market value of the service provided, then itemize that value in the charitable donations section of their Federal income tax return. Is there any reason why coders on open source projects who choose to donate their personal copyright (i.e., their coding) to the main project (as long as it is a registered non-profit) couldn't claim a tax deduction for a gift of in-kind professional services? If so, this could provide a measure of compensation to open source coders.