What if we could provide this with tooling? Like, everyone that uses Go for an extended period eventually complains about how it's an error to import a module and not use it... until they enable goimports-on-save and then the problem vanishes (mostly). (My point is not to compare go/rust module systems but to illuminate how a pain point introduced by the language's guarantees can be eliminated by tooling.)
If there is such an easy to define 1:1 mapping, then could there be a rustmods-on-save tool that automatically adds mod statements according to a fixed scheme whenever any *.rs file is created in the current directory or a child directory?