Unlike the ones you mentioned, Go doesn't have a central repository. The go.mod contains references to git repositories or local folders:
https://go.dev/doc/modules/gomod-ref
Not sure why a proxy is needed.
https://go.dev/doc/modules/gomod-ref
Not sure why a proxy is needed.
Maybe I'm missing something, but this whole operation feels like a huge infrastructure paid by Google for something that is not needed.
Git uses SHA1 which is pretty far from cryptographically secure. It’s unlikely that’s the sole reason for having a separate checksum database though.
As sibling comment notes, Git's hashes are not secure: https://shattered.it