I agree with you! 503c3’s for instance, ARE coporations!
If you want some education on the matter check out USPS "nonprofit" rules ~ they are clear, concise, and more informative than the IRS rules.
The difference is USPS is trying to sell you on qualifying and IRS is attempting to trip you up so you commit tax fraud and can be sent to prison.
All sarcasm aside, USPS rules are shorter and clearer. Virtually all 501C3's of thesame category would qualify for discounted postage for bulk mailings ~ on the other hand, a lot of the IRS rules are INCOMPREHENSIBLE BY NORMAL PEOPLE.