US copyright law cares about originality and expressiveness, not labour and cost. It can be very expensive to collect and print a list of every business and their phone number in a book, but the result is not copyrightable in the US.
Would it makes sense to say a "give me a rowboat on the water" prompt (search) is the same as a "give me the phone number of company XYZ" search in a phonebook?
What exactly is a prompt anyway? Can you copyright the assembly that a compiler spits out? Is an AI prompt the same as source code and its output is the assembly a compiler would generate? Does that mean the model is a compiler? I assume a compiler can be copyrighted, so then maybe the weights can be copyrighted? Or would it make more sense that the combination of (weights + prompt + seed + output) is copyrightable?
I don't have answers to any of these or know if they're reasonable questions but I'm starting to find this all very fascinating.