When I was a medical student doing my family medicine rotation, I worked in an outpatient clinic which was staffed by both doctors and nurse practitioners. As far as I could tell, the doctors and the nurse practitioners did pretty much the same job.
However, in the parking lot, which had ample parking, there were two physician parking spots right by the door. Not that there were any parking spots that were very far away, but these physicians spots were a little bit closer.
There was one doctor who worked at the clinic named Dr. Green, who went on at least two rants during my time working there about the fact that sometimes nurse practitioners would park in the physician spots. Dr. Green got really angry about it. He went so far as to make fun of the nurses who did it by calling them "doctor" facetiously.
My husband says that there is no need for physician spots and it's all just vanity, but there have been times in my career when I really needed a physician spot, such as when I had to race across a crowded parking lot to get to an emergency in the hospital. Or at two in the morning, when I had to treck 15 minutes in a dark desolate area to get to an emergency because there were no physician spots by the hospital. So it's not all about vanity. But I also feel like in an outpatient clinic, it sort of is about vanity.