Right after purchasing my Model 3 last fall, my daughter and I went on a road trip. Our next stop was near the max range of the car, so I plugged it in and charged it to max outside Portland, Oregon. We went inside for lunch while waiting. We spent longer than we had planned inside the restaurant. When we came back, someone had kindly taken a dirty diaper and written on our windows, "N00B CHARGE". The diaper was stuffed under the wipers. I wish I had had Sentry Mode at that point....
Anyway, don't touch someone else's car! A simple "rules of charging" business card tucked into the windshield/doorjam is one thing, but don't be an ass. At the same time, geofencing would be welcome.