If Cadillac has a less wealthy clientele that has lower expectations, those results aren't really indicative of a superior experience... are they?
The logic of your position would have Land Rover dealers as being the worst in the known Universe.
One thing I find interesting with charts like this is the inverse relationship between "satisfaction", and "perception".
Land Rover as a brand is generally held in very high esteem by the public at large, but considerably less so by the people who actually buy them and have to spend so much time at the dealerships this chart would indicate they dislike so much.
It would also appear that satisfaction with dealers has POSITIVELY NO EFFECT ON SALES.