"The public" funds McDonalds, then. My buying a hamburger doesn't mean I get the rights to the McDonalds trademark.

People donate to NPR of their own free will with the complete understanding that they're doing it as a donation, not as a "make our content public domain" licensing agreement. A pledge drive donation isn't a purchase, you haven't paid for anything, for the same reasons donating to Obama's campaign didn't buy you a night in the Lincoln Bedroom.