The consensus on this site is that the pin placement on Tesla's maps is merely a general location and not a specific location. Likely the Santa Rosa/Monterey intersection is considered the heart of San Luis. Similarly the "coming soon" for Fresno reflects a pin just off highway 41 in a real crappy part of town that has no redeeming places to plug in, let alone do something for 30-45 minutes.
Moreover, Tesla tries its best to locate Supercharger spots with fairly easy ingress and egress from the freeways. Madonna Inn fits that ideal perfectly. Santa Rosa and Monterey, not so much.
But we shall see!