It's only a mess because not everyone has adopted uv yet (IMO)

Yep. The lesson is to get this right early in your language design. Do not punt until version 2.0. Think twice before putting the package/module/whatever metadata in an executable script. If you do decide to do that, think a third time. It works out better for some languages (like Common Lisp) than others (like Python).

never had a problem with dependencies. how is it a mess? you have requirements.txt and venv per project. doesn't get easier than that

Yes, it's a mess (New: now with Rust!)