Now that is scary! Imagine if you could not grab it time and someone was in the way. It's only matter of time before we hear of people getting run over (assuming it hasn't happened already). I'm afraid to even use it in my driveway. Even with the continuous press, there could still be a glitch that causes the car not to stop even after losing communication.
At least when inside the car, the driver can still hit the brakes. Outside, one is putting total trust in a computer. There's a video on Youtube with a smart summoned Model 3 taking a longer route in the opposite direction. There was hardly anyone around, but it's not hard to imagine it trying to navigate a crowded area on its own. Crazy.