Carrara doesn't think of .eps as a vector art format but an image format instead. So, you can import a picture saved in an .eps format in the vertex room as a backdrop or as a background for a render - but not as a path document. 

It's the same thing for the .dxf format which is a CAD format. But many CAD systems export .dxf as a flat image format for blueprints. Carrara "thinks" about .eps that way too. 

I don't agree with the implementation but that's how it works. :-/

Mark