I think the fundamental difference is that Git is a CLI tool. But that's not how or where people use and want to use it. So obviously various interfaces are being created. It's not alternative CLI that are created. It's UIs and GUI interfaces. For a lack of a [more-than-barebone] official one.
Shells remain CLI. Distros are also technically/technologically driven.
Maybe the better analogy is that with vim and nano, we see many text editors and IDEs with GUIs.