I've been looking at some repaints that people have done on their cabinets, I'm by no means trying to knock their work, but I've noticed this little detail missing.
I had one guy not know what it was when he was repainting his cabinet until I pointed it out to him. I also wasn't sure in the beginning, but now I know.
I think they are leaving it out because it's a very hard nail to find or they just don't know what it is and they leave it off.
This little nail is there to keep the coin return button from chipping the paint if you swing the coin door open too much. See picture
I'm sure no one ever thinks they will swing the coin door open too far until they accidentally do just FYI