Part of is is probably because subfolders are subpackages and relative imports don't work and absolute imports have other issues - like causing issues with forking.
IIRC the tooling is not smart enough to resolve them when you import a subpackage directly.
I was working on a go project and I had to convert all of the relative imports to absolute imports for some reason, but the exact cause escapes my memory.
Really ? Is that a bug, or by design ? If the later, what's the rationnal about it ?