Non-profits are different in the sense that there are a different set of laws they have to follow, and a core mission that is held to much moreso than in private industry. The laws make non-profits make vastly different decisions than a for-profit would make. Furthermore, non-profits hire people who are passionate about what they work on, which means hiring and culture is different (not based nearly as much on money/payout).
As for a "philanthropic exchange" API, I imagine they are busy just keeping everything running at the moment, let alone trying for something far-sweeping and loosely defined as that.
There are such laws on the books in at least some U.S. jurisdictions, but it doesn't really cause anybody to lose their tax status because there are legal workarounds. It is very common for a nonprofit organization's Articles of Incorporation (and any other legally-binding statements of purpose) to be written like this:
"This benevolent, charitable and eleemosynary institution has been organized [...under the appropriate state law for a charitable organization...] and shall be operated exclusively for charitable, religious, educational, literary, or scientific purposes within the meaning of §501(c)(3) of the U.S. Internal Revenue Code of 1986 as the same may be amended from time to time. Within the foregoing purposes and not by way of limitation, [the organization shall perform its core mission]."