I was wondering what was being used to control the car. As an owner, I suppose you'd know if WiFi was a possibility.I can't remember if summon works through the phone and car's cellular data connection or if it's through Bluetooth. I know that one of the complaints about the feature is that you have to be relatively close to the car but that still seems like it might be out of Bluetooth range.
The distance is 6 meters? Unless people parked close to you so it is difficult getting back into the car, I don't see the use of this feature as I should be able to walk about 20 feet.
https://www.tesla.com/ownersmanual/modely/is_is/GUID-6B9A1AEA-579C-400E-A7A6-E4916BCD5DED.html
Smart Summon works with the Tesla mobile app when your phone is located within approximately 6 meters of Model Y.
This statement suggests it uses cellular data:
Smart Summon's performance depends on the ultrasonic sensors, the visibility of the cameras, and the availability of an adequate cellular signal and GPS data.