Not all workplaces are high functioning in the way you imagine. Until recently a shocking amount of software development did not use source control.
I don't think that many teams review commit messages as a part of code review. At least, I've never seen it "in the wild".
True, is mostly about the code being merged, but when reviewing a PR they might suggest that the dev write better commit messages in the future.
We have standards we ask devs to follow but I’m not going to make someone go back and change a commit message after the fact. I more care about pull request body copy and I think the rules we have for that have been pretty well adhered too. Don’t even need ai to enforce it.