I've said it before and I'll say it again:
the most important thing to consider is a test's audience
You're grating at this request precisely because this busy work could force the tests audience to change which changes the purpose of the test. That can have a profound impact. If that's where this is headed, stop it now.
However, while these tests are not identical, they are linked.
That is, this working
AC1 Verify that on the page load customers list is displayed
depends on this working
so long as the page load uses
Now that is something you can map. You can map it with a comment in the test:
Standardize that comment and you can automate the mapping. But all this documents is that, at one point at least, AC1 depended on the method tested here working. That can change for reasons that have nothing to do with this methods implementation or its unit test. That dependency is controlled in the page.
And that's the rub when you start documenting things like that. You're actually making it harder to make changes by doing this. Because now you have to track down everywhere this dependency is expressed any time you make a change to it. You're going to hate that every code change means changing everything it's no longer using to keep this report updated.
The payoff is less manual testing. If people can trust the automated test suite (which is more than just unit tests) you don't need to wait through 6 months of manual testing before each release.
So I'll emphasize this again. These are different tests. They serve different audiences. They mean different things. Each can pass and fail independent of the other. But if no one's changed how the page works the page will fail to load when the method fails. This can be a useful thing to report. But it is not a change friendly report. This report locks you down. Therefor automate the report as best you can. Make it as easy to update as you can. Because otherwise you're casting your code in cement.
Now if you had a tool that could automate mapping from AC1 to the page load, to the page load methods, to those methods tests, to the results of those tests, all without that stupid standardized comment, well then you'd really have something nifty.