Look at the big picture. The maintainers likely deal with many low-quality bug reports and PRs coming in, especially from AI, and the incentive to spam these is not going away anytime soon. How should they best allocate their limited attention?

One way is for the PR maker to signal their own attention to detail/effort/commitment by jumping through the (quite reasonable) hoop of writing a test.

Is this extra effort? Yes. But if your motivation in opening the PR in the first place is genuinely to improve the world, then do the slightly harder thing that actually improves the world given the constraints on maintainer attention it operates under, not the thing that is slightly easier for you but leaves your contribution indistinguishable from the sea of slop out there.