It's usually easier than that, as one by default hold the copyright of their works. Typically a company doesn't need to provide the whole working process and files to the court to claim copyright over their published products / to accuse pirates for violation.

If you're on the defendant side of a copyright violation case, it's extremely hard to use "well the original author didn't really make it...* as a defense. (Patent cases are often defended with this argument though, as a patent grants far boarder protection than copyright and can be rejected on prior art. But still it's very different from "AI made this actually.")