Because the non-programmers didn't write it. That's how copyright works, and it's why big companies are so careful about this, and make you sign reams of papers.

This is also why it's such a pain in the ass for open source projects to changes licenses -- they have to get permission from everyone and anyone who contributed code, or rewrite that person's contributions.

You write it, you own the copyright for whatever part you wrote unless you formally transfer your copyright via contract. You don't even have to file any papers to get copyright, it's automatic.

thanks for the clarification - the part about not having to file any papers is something I didn't understand at all.

So in this example of startup weekend, whoever writes a piece of code owns it, whoever writes website copy owns it and so on and so forth to the extent that the startup weekend ip policy doesn't setup something different for participants.

(edit: fixed the last paragraph)

All of them can and all of them have to buy in to licensing it. Similar to when an open source project wants to change licenses (for some licenses), they need to reach out to every contributor and get an agreement from them.