You're probably referring to parking sensors, which are typically ultrasonic sensors mounted to the bumpers. Unfortunately, ultrasonics have both a limited range of ~20ft for practical uses, and more damningly, a relatively wide field of view with no ability to distinguish where in the field of view an object is. While 20ft range is more than enough to give you time to slam on the brakes in your garage, it's basically useless for high speed autonomy, except for some very limited blindspot-awareness type tasks.
It's not a parking sensor and there isn't anything on the bumper as far as i can tell. It's toyotas precollision system that uses a simple radar and a cheap camera. It even brakes for you if you don't.
