I remember having tried it once and abandoning because it lacked this feature (or didn't work out of the box).
If you are using it with something like fuse or expandrive you are not using it over SSH but on local files.
If you are using it in a remote Vim via SSH, you are not using it over SSH either.
If you did something like :e scp://foo//bar/ and see a directory listing you are not using NERDTree.