just figured it out… the lines in fritzing are traces for drawing and not paths for etching/milling.
so I step it through Inkscape to turn the drawing paths into an outline (which makes it a milling path)
Open the *yourfilename*_etch_copper_bottom_mirror.svg in Inkscape, select everything and repeatedly press ctrl+shift+g until everything is ungrouped.
Select view -> display mode -> outline. You will now see only the vectors without fill or stroke.
Select all traces and go to Path -> Stroke to Path.
Select all traces and go to Path -> Union.
that gets this SVG which opens like so in estlcam