Because it's different from a passive tool like keyboard you are using for typing your creation and such. The program actively creates something. Author of the

Because it's different from a passive tool like keyboard you are using for typing your creation and such. The program actively creates something. Author of the program isn't creating the result, the program is. As I said in the second comment, the whole idea of copyright is based on the incentive. Once that program is out, the author of the program doesn't do anything, i.e. idea of incentive is irrelevant to the resulting works. You can take it to absurd level. Let's say you write a program that generates every possible text combination, increasingly. Does it mean the author of the program should have copyright potentially on every (not yet copyrighted) text? Of course not, even if resulted texts are original and not gibberish. Same applies to any media, not just text of course.