@feld >the code is trivial and not patentable
Software is not a patentable subject manner, as software is math - too bad the USA patent office awards them anyway.

A patent on one program wouldn't be a big issue - the issue is that patents restrict all software and even hardware.

The relevant law here is copyright.

While "return 0;" certainly isn't creative enough to qualify for copyright, based GNU developers decided to exercise their creativity and write yet another masterpiece (https://git.savannah.gnu.org/cgit/coreutils.git/tree/src/true.c) that is creative enough to qualify for copyright and therefore it print the license.