Anecdotally, I see them all the time in my neighborhood, and they seem much more attentive to pedestrians and stop signs than regular drivers. Drivers in this neighborhood act like they own the place even though there's probably an equal number of pedestrians out at any given time.
I've also seen one of them fail to pull over when an emergency vehicle was behind it, so I buy that they are causing some problems.
I agree with you. Something about the grease does not sit right with me. The last time I had wagyu, it was at a fancy restaurant tasting menu place where each dish contained some part of the animal. I ended up throwing up later that evening.