The problem is that licensing under the same terms is not enough for most corporate open source stewards. They want copyright assignment, meaning you give them all of your rights.
> The contribution bot asks for confirmation the code change is copyright-free, but the contributor doesn’t respond.
Maybe the author is summarizing though and the bot asks the author to confirm it's copyright free and also to sign the CLA/DCO. If so, unlikely their corporate overlord would be OK with them just merging the PR without explicitly signed CLA/DCO.
This issue of "how can we ensure this code is under copyright terms XYZ" seems to have been popularly solved by CLA's. And thus a pall has been cast over the traditional open source dynamic, where there'd normally be no question that a fork with a license in the repo is obviously licensed under the same terms.
I've heard this on legal podcasts as well. Where lawyers spend like 30+ minutes talking about whether a license in the project root counts. To the traditional free software / open source movement, this seems really silly, because that's how software projects worked for almost the entire existence of free software / open source software until the last 5-ish years.