Earlier quoted context omitted.
Maybe the solution here is do adopt the approach from humans: if you independently produce someone's copyrighted work and then discover about it - you'll drop it. The same approach could be used here, they can add a check for the similarity between the output and the original training material, if it is above a threshold, they'll drop the suggestion (maybe they are already doing that).
That doesn't work, though - the problem is you have automated crime. When you do this, you can no longer handle this on a case by case basis - you have to resort to automating justice. And at this point, you are getting both attacked and supported by AI, and not really better off in a meaningful way. There's no good way of solving this issue, without general intelligence, and the problems that will bring (what reason…
I don’t think AI research in a vacuum is as deeply unethical as you suggest. It’s about current societal context- people won’t like being worse at things; resources will be hoarded rather than distributed.