This is unfortunate, because it means that one needs to have different configurations for different environments, which means that bugs will creep into the live site because the config that goes live can’t be tested in dev or CI.
Is there really no way to make all URLs relative in HUGO? It’s a fundamental part of the HTML spec, and exists specifically to avoid requiring separate builds, or code changes just because you moved the site. I would have expected relative links to be the default behavior…