Someones not pulling thier weight...
A move toward high-riding vehicles helped one brand. A move away from traditional cars harmed the other. These two factors are made all the more apparent when one brand employs a full lineup of SUVs/crossovers and the other has yet to bring its first utility vehicle to market.
One brand’s message has been artfully constructed over a few decades; the other’s has been muddied for at least a generation.
Both have been labelled as dreadfully unreliable at different points. One brand has had trouble discarding that label; the other has succeeded in spite of it.