It's like things that are already in public domain. Even if you make a coloring book out of paintings in public domain, it doesn't necessarily mean others can just print your book as-is.
Have you been involved in copyright or patent litigation?
Because it's not that easy.
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.")
That's not what we're talking about.
This is a question of copyright eligibility in the first place. An excellent recent(ish) example is Oracle v Google wherein the former claimed copyright over the Java APIs. That particular litigation went on for years and ultimately went to the Supreme Court (though it ultimately ended on a fair use argument and the issue of API copyright eligibility was never settled).
We can probably assume similar high profile cases in the future that turn on quantifying the level of human contribution in code produced through the use of AI.
As for patents, it's literally that easy. Attacking authorship of a patent is an excellent way to invalidate it. It's why any company with a serious patent program requires staff to keep supporting notes for their work and confirm authorship in writing as part of the filing process.
If companies get slope with creative output to the point that "a few employees" can reproduce it in shadow markets, don't expect to get copyright protection without giving governments revenue and speech-control.